Communication system, base station and terminal device

ABSTRACT

A cell2 configured by only a DL CC2 being a resource for downlink is configured. The cell2 does not include a resource for uplink, that is, a UL CC to be associated with the DL CC2 by a DL/UL link. The link information indicating the above is notified a communication terminal device by a base station device using the DL CC2. A DL CC1 and a UL CC1 constitute a cell1. The downlink communication from the base station device to the communication terminal device is performed using the cell1 and the cell2, and the uplink communication from the communication terminal device to the base station device is performed using the cell1.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/230,486 filed Dec. 21, 2018, which is a continuation of U.S.application Ser. No. 15/956,384 filed Apr. 18, 2018, which is adivisional of U.S. application Ser. No. 15/163,216 filed May 24, 2016,which is a divisional of U.S. application Ser. No. 13/978,622 filed Jul.8, 2013, which is a National Phase of PCT/JP2011/079484 filed Dec. 20,2011, and claims priority to Japanese Patent Application No. 2011-001684filed Jan. 7, 2011. The entire contents of each of which areincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a base station device that performsradio communication with a plurality of communication terminal devicesand a communication system including the same.

BACKGROUND ART

Commercial service of a wideband code division multiple access (W-CDMA)system among so-called third-generation communication systems has beenoffered in Japan since 2001. In addition, high speed downlink packetaccess (HSDPA) service for achieving higher-speed data transmissionusing a downlink has been offered by adding a channel for packettransmission (high speed-downlink shared channel (HS-DSCH)) to thedownlink (dedicated data channel, dedicated control channel). Further,in order to increase the speed of data transmission in an uplinkdirection, service of a high speed uplink packet access (HSUPA) systemhas been offered. W-CDMA is a communication system defined by the 3rdgeneration partnership project (3GPP) that is the standard organizationregarding the mobile communication system, where the specifications ofRelease 8 version are produced.

Further, new communication systems referred to as long term evolution(LTE) regarding radio areas and system architecture evolution (SAE)regarding the overall system configuration including a core network(merely referred to as network as well) as communication systemsindependent of W-CDMA is studied in 3GPP. This communication system isalso referred to as 3.9 generation (3.9 G).

In the LTE, an access scheme, a radio channel configuration and aprotocol are totally different from those of the current W-CDMA(HSDPA/HSUPA). For example, as to the access scheme, code divisionmultiple access is used in the W-CDMA, whereas in the LTE, orthogonalfrequency division multiplexing (OFDM) is used in a downlink directionand single career frequency division multiple access (SC-FDMA) is usedin an uplink direction. In addition, the bandwidth is 5 MHz in theW-CDMA, while in the LTE, the bandwidth can be selected from 1.4 MHz, 3MHz, 5 MHz, 10 MHz, 15 MHz and 20 MHz per base station. Further,differently from the W-CDMA, circuit switching is not provided but apacket communication system is only provided in the LTE.

The LTE is defined as a radio access network independent of the W-CDMAnetwork because its communication system is configured by a new corenetwork different from a core network (general packet radio service:GPRS) of the W-CDMA. Therefore, for differentiation from the W-CDMAcommunication system, a base station that communicates with a userequipment (UE) and a radio network controller that transmits/receivescontrol data and user data to/from a plurality of base stations arereferred to as an E-UTRAN NodeB (eNB) and an evolved packet core (EPC)or access gateway (aGW), respectively, in the LTE communication system.

Unicast service and evolved multimedia broadcast multicast service(E-MBMS service) are provided in this LTE communication system. TheE-MBMS service is broadcast multimedia service, which is merely referredto as MBMS in some cases. Bulk broadcast contents such as news, weatherforecast and mobile broadcast are transmitted to a plurality of userequipments. This is also referred to as point to multipoint service.

Non-Patent Document 1 (Chapter 4) describes the current decisions by3GPP regarding an overall architecture in the LTE system. The overallarchitecture is described with reference to FIG. 1. FIG. 1 is a diagramillustrating the configuration of the LTE communication system. Withreference to FIG. 1, the evolved universal terrestrial radio access(E-UTRAN) is composed of one or a plurality of base stations 102,provided that a control protocol for a user equipment 101 such as aradio resource control (RRC) and user planes such as a packet dataconvergence protocol (PDCP), radio link control (RLC), medium accesscontrol (MAC) and physical layer (PHY) are terminated in the basestation 102.

The base stations 102 perform scheduling and transmission of pagingsignal (also referred to as paging messages) notified from a mobilitymanagement entity (MME) 103. The base stations 102 are connected to eachother by means of an X2 interface. In addition, the base stations 102are connected to an evolved packet core (EPC) by means of an S1interface. More specifically, the base station 102 is connected to themobility management entity (MME) 103 by means of an S1_MME interface andconnected to a serving gateway (S-GW) 104 by means of an S1_U interface.

The MME 103 distributes the paging signal to a plurality of or a singlebase station 102. In addition, the MME 103 performs mobility control ofan idle state. When the user equipment is in the idle state and anactive state, the MME 103 manages a list of tracking areas.

The S-GW 104 transmits/receives user data to/from one or a plurality ofbase stations 102. The S-GW 104 serves as a local mobility anchor pointin handover between base stations. Moreover, a PDN gateway (P-GW) isprovided in the EPC, which performs per-user packet filtering and UE-IDaddress allocation.

The control protocol RRC between the user equipment 101 and the basestation 102 performs broadcast, paging, RRC connection management andthe like. The states of the base station and the user equipment in RRCare classified into RRC_IDLE and RRC_CONNECTED. In RRC_IDLE, public landmobile network (PLMN) selection, system information (SI) broadcast,paging, cell reselection, mobility and the like are performed. InRRC_CONNECTED, the user equipment has RRC connection, is capable oftransmitting/receiving data to/from a network, and performs, forexample, handover (HO) and measurement of a neighbor cell.

The current decisions by 3GPP regarding the frame configuration in theLTE system described in Non-Patent Document 1 (Chapter 5) are describedwith reference to FIG. 2. FIG. 2 is a diagram illustrating theconfiguration of a radio frame used in the LTE communication system.With reference to FIG. 2, one radio frame is 10 ms. The radio frame isdivided into ten equally sized subframes. The subframe is divided intotwo equally sized slots. The first and sixth subframes contain adownlink synchronization signal (SS) per each radio frame. Thesynchronization signals are classified into a primary synchronizationsignal (P-SS) and a secondary synchronization signal (S-SS).

Multiplexing of channels for multimedia broadcast multicast servicesingle frequency network (MBSFN) and for non-MBSFN is performed on aper-subframe basis. MBSFN transmission is a simulcast transmissiontechnique realized by simultaneous transmission of the same waveformsfrom a plurality of cells. The MBSFN transmission from a plurality ofcells in the MBSFN area is seen as a single transmission by a userequipment. The MBSFN is a network that supports such MBSFN transmission.Hereinafter, a subframe for MBSFN transmission is referred to as MBSFNsubframe.

Non-Patent Document 2 describes a signaling example when MBSFN subframesare allocated. FIG. 3 is a diagram illustrating the configuration of theMBSFN frame. With reference to FIG. 3, a radio frame including the MBSFNsubframes is allocated per radio frame allocation period. The MBSFNsubframe is a subframe allocated for the MBSFN in a radio frame definedby the allocation period and the allocation offset (radio frameallocation offset), and serves to transmit multimedia data. The radioframe satisfying Equation (1) below is a radio frame including the MBSFNsubframes.SFN mod radioFrameAllocationPeriod=radioFrameAllocationOffset  (1)The MBSFN subframe is allocated with six bits. The leftmost bit definesthe MBSFN allocation for the second subframe (#1). The second bit, thirdbit, fourth bit, fifth bit, and sixth-bit define the MBSFN allocationfor the third subframe (#2), fourth subframe (#3), seventh subframe(#6), eighth subframe (#7), and ninth subframe (#8), respectively. Thecase where the bit indicates “one” represents that the correspondingsubframe is allocated for the MBSFN.

Non-Patent Document 1 (Chapter 5) describes the current decisions by3GPP regarding the channel configuration in the LTE system. It isassumed that the same channel configuration is used in a closedsubscriber group cell (CSG cell) as that of a non-CSG cell. Physicalchannels are described with reference to FIG. 4. FIG. 4 is a diagramillustrating physical channels used in the LTE communication system.

With reference to FIG. 4, a physical broadcast channel (PBCH) 401 is adownlink channel transmitted from the base station 102 to the userequipment 101. A BCH transport block is mapped to four subframes withina 40 ms interval. There is no explicit signaling indicating 40 mstiming. A physical control format indicator channel (PCFICH) 402 istransmitted from the base station 102 to the user equipment 101. ThePCFICH notifies the number of OFDM symbols used for PDCCHs from the basestation 102 to the user equipment 101. The PCFICH is transmitted in eachsubframe.

A physical downlink control channel (PDCCH) 403 is a downlink channeltransmitted from the base station 102 to the user equipment 101. ThePDCCH notifies the resource allocation of DL-SCH ((downlink sharedchannel that is one of the transport channels shown in FIG. 5 describedbelow) and PCH (paging channel that is one of the transport channelsshown in FIG. 5), and HARQ information related to DL-SCH. The PDCCHcarries an uplink scheduling grant. The PDCCH carries acknowledgement(Ack)/negative acknowledgement (Nack) that is a response signal touplink transmission. The PDCCH is referred to as an L1/L2 control signalas well.

A physical downlink shared channel (PDSCH) 404 is a downlink channeltransmitted from the base station 102 to the user equipment 101. ADL-SCH (downlink shared channel) that is a transport channel and a PCHthat is a transport channel are mapped to the PDSCH. A physicalmulticast channel (PMCH) 405 is a downlink channel transmitted from thebase station 102 to the user equipment 101. A multicast channel (MCH)that is a transport channel is mapped to the PMCH.

A physical uplink control channel (PUCCH) 406 is an uplink channeltransmitted from the user equipment 101 to the base station 102. ThePUCCH carries Ack/Nack that is a response signal to downlinktransmission. The PUCCH carries a channel quality indicator (CQI)report. The CQI is quality information indicating the quality ofreceived data or channel quality. In addition, the PUCCH carries ascheduling request (SR). A physical uplink shared channel (PUSCH) 407 isan uplink channel transmitted from the user equipment 101 to the basestation 102. A UL-SCH (uplink shared channel that is one of thetransport channels shown in FIG. 5) is mapped to the PUSCH.

A physical hybrid ARQ indicator channel (PHICH) 408 is a downlinkchannel transmitted from the base station 102 to the user equipment 101.The PHICH carries Ack/Nack that is a response to uplink transmission. Aphysical random access channel (PRACH) 409 is an uplink channeltransmitted from the user equipment 101 to the base station 102. ThePRACH carries a random access preamble.

A downlink reference signal is a known symbol in a mobile communicationsystem. The physical layer measurement objects of a user equipmentinclude reference symbol received power (RSRP).

The transport channels described in Non-Patent Document 1 (Chapter 5)are described with reference to FIG. 5. FIG. 5 is a diagram illustratingtransport channels used in the LTE communication system. Part (A) ofFIG. 5 shows mapping between a downlink transport channel and a downlinkphysical channel. Part (B) of FIG. 5 shows mapping between an uplinktransport channel and an uplink physical channel.

A broadcast channel (BCH) is broadcast to the entire coverage of a basestation (cell) regarding the downlink transport channel. The BCH ismapped to the physical broadcast channel (PBCH).

Retransmission control according to a hybrid ARQ (HARQ) is applied to adownlink shared channel (DL-SCH). The DL-SCH enables broadcast to theentire coverage of the base station (cell). The DL-SCH supports dynamicor semi-static resource allocation. The semi-static resource allocationis also referred to as persistent scheduling. The DL-SCH supportsdiscontinuous reception (DRX) of a user equipment for enabling the userequipment to save power. The DL-SCH is mapped to the physical downlinkshared channel (PDSCH).

The paging channel (PCH) supports DRX of the user equipment for enablingthe user equipment to save power. The PCH is required to broadcast tothe entire coverage of the base station (cell). The PCH is mapped tophysical resources such as the physical downlink shared channel (PDSCH)that can be used dynamically for traffic.

The multicast channel (MCH) is used for broadcast to the entire coverageof the base station (cell). The MCH supports SFN combining of MBMSservice (MTCH and MCCH) in multi-cell transmission. The MCH supportssemi-static resource allocation. The MCH is mapped to the PMCH.

Retransmission control according to a hybrid ARQ (HARQ) is applied to anuplink shared channel (UL-SCH). The UL-SCH supports dynamic orsemi-static resource allocation. The UL-SCH is mapped to the physicaluplink shared channel (PUSCH).

A random access channel (RACH) shown in part (B) of FIG. 5 is limited tocontrol information. The RACH involves a collision risk. The RACH ismapped to the physical random access channel (PRACH).

The HARQ is described. The HARQ is the technique for improving thecommunication quality of a channel by combination of automatic repeatrequest and error correction (forward error correction). The HARQ has anadvantage that error correction functions effectively by retransmissioneven for a channel whose communication quality changes. In particular,it is also possible to achieve further quality improvement inretransmission through combination of the reception results of the firsttransmission and the reception results of the retransmission.

An example of the retransmission method is described. In a case wherethe receiver fails to successfully decode the received data, in otherwords, in a case where a cyclic redundancy check (CRC) error occurs(CRC=NG), the receiver transmits “Nack” to the transmitter. Thetransmitter that has received “Nack” retransmits the data. In a casewhere the receiver successfully decodes the received data, in otherwords, in a case where a CRC error does not occur (CRC=OK), the receivertransmits “AcK” to the transmitter. The transmitter that has received“Ack” transmits the next data.

Examples of the HARQ system include chase combining. In chase combining,the same data is transmitted in the first transmission andretransmission, which is the system for improving gains by combining thedata of the first transmission and the data of the retransmission inretransmission. This is based on the idea that correct data is partiallyincluded even if the data of the first transmission contains an error,and highly accurate data transmission is enabled by combining thecorrect portions of the first transmission data and the retransmissiondata. Another example of the HARQ system is incremental redundancy (IR).The IR is aimed to increase redundancy, where a parity bit istransmitted in retransmission to increase the redundancy by combiningthe first transmission and retransmission, to thereby improve thequality by an error correction function.

A logical channel described in Non-Patent Document 1 (Chapter 6) isdescribed with reference to FIG. 6. FIG. 6 is a diagram illustratinglogical channels used in an LTE communication system. Part (A) of FIG. 6shows mapping between a downlink logical channel and a downlinktransport channel. Part (B) of FIG. 6 shows mapping between an uplinklogical channel and an uplink transport channel.

A broadcast control channel (BCCH) is a downlink channel for broadcastsystem control information. The BCCH that is a logical channel is mappedto the broadcast channel (BCH) or downlink shared channel (DL-SCH) thatis a transport channel.

A paging control channel (PCCH) is a downlink channel for transmittingchanges of the paging information and system information. The PCCH isused when the network does not know the cell location of a userequipment. The PCCH that is a logical channel is mapped to the pagingchannel (PCH) that is a transport channel.

A common control channel (CCCH) is a channel for transmission controlinformation between user equipments and a base station. The CCCH is usedin a case where the user equipments have no RRC connection with thenetwork. In a downlink direction, the CCCH is mapped to the downlinkshared channel (DL-SCH) that is a transport channel. In an uplinkdirection, the CCCH is mapped to the uplink shared channel (UL-SCH) thatis a transport channel.

A multicast control channel (MCCH) is a downlink channel forpoint-to-multipoint transmission. The MCCH is used for transmission ofMBMS control information for one or several MTCHs from a network to auser equipment. The MCCH is used only by a user equipment duringreception of the MBMS. The MCCH is mapped to the multicast channel (MCH)that is a transport channel.

A dedicated control channel (DCCH) is a channel for point-to-pointtransmission of the dedicated control information between a userequipment and a network. The DCCH is used when a user equipment is inRRC connection. The DCCH is mapped to the uplink shared channel (UL-SCH)in uplink and mapped to the downlink shared channel (DL-SCH) indownlink.

A dedicated traffic channel (DTCH) is a point-to-point communicationchannel for transmission of the user information to a dedicated userequipment. The DTCH exists in uplink as well as downlink. The DTCH ismapped to the uplink shared channel (UL-SCH) in uplink and mapped to thedownlink shared channel (DL-SCH) in downlink.

A multicast traffic channel (MTCH) is a downlink channel for trafficdata transmission from a network to a user equipment. The MTCH is achannel used only by a user equipment during reception of the MBMS. TheMTCH is mapped to the multicast channel (MCH).

GCI represents a global cell identity. A closed subscriber group cell(CSG cell) is introduced in the LTE, long term evolution advanced(LTE-A) described below, and universal mobile telecommunication system(UMTS). The CSG is described below (see Chapter 3.1 of Non-PatentDocument 3). The closed subscriber group (CSG) cell is a cell in whichsubscribers who are allowed to use are specified by an operator(hereinafter, referred to as “cell for specific subscribers” in somecases).

The specified subscribers are allowed to access one or more cells of apublic land mobile network (PLMN). One or more cells in which thespecified subscribers are allowed access are referred to as “CSGcell(s)”. Note that access is limited in the PLMN. The CSG cell is partof the PLMN that broadcasts a specific CSG identity (CSG ID; CSG-ID) andbroadcasts “TRUE” by CSG indication. The authorized members of thesubscriber group who have registered in advance access the CSG cellsusing the CSG-ID that is the access permission information.

The CSG-ID is broadcast by the CSG cell or cells. A plurality of CSG-IDsexist in a mobile communication system. The CSG-IDs are used by userequipments (UEs) for making access from CSG-related members easier.

The locations of user equipments are tracked based on an area composedof one or more cells. The locations are tracked for enabling tracking ofthe locations of user equipments and calling (calling of userequipments) even in an idle state. An area for tracing locations of userequipments is referred to as a tracking area.

A CSG whitelist is a list that may be stored in a universal subscriberidentity module (USIM) in which all CSG IDs of the CSG cells to whichthe subscribers belong are recorded. The CSG whitelist is also referredto as an allowed CSG list in some cases.

Service types of a user equipment in an idle state are described below(see Chapter 4.3 of Non-Patent Document 3). The service types of a userequipment in an idle state are classified into limited service (alsoreferred to as closed service), a normal service, and an operatorservice. The limited service includes emergency calls, an earthquake andtsunami warning system (ETWS), and a commercial mobile alert system(CMAS) on an acceptable cell described below. The normal service (alsoreferred to as standard service) is the service for public use on asuitable cell described below. The operator service is the service foroperators only on a reserved cell described below.

A “suitable cell” is described below. The “suitable cell” is a cell onwhich a UE may camp to obtain normal service. Such a cell shall fulfillthe following conditions (1) and (2).

(1) The cell is part of the selected PLMN or the registered PLMN, orpart of the PLMN of an “equivalent PLMN list”.

(2) According to the latest information provided by a non-access stratum(NAS), the cell shall further fulfill the following conditions (a) to(d):

(a) the cell is not a barred cell;

(b) the cell is part of a tracking area (TA), not part of the list of“forbidden LAs for roaming”, where the cell needs to fulfill (1) above;

(c) the cell shall fulfill the cell selection criteria; and

(d) for a cell specified as CSG cell by system information (SI), theCSG-ID is part of a “CSG whitelist” of the UE (contained in the CSGwhitelist of the UE).

An “acceptable cell” is described below. This is the cell on which a UEmay camp to obtain limited service. Such a cell shall fulfill the allfollowing requirements.

(1) The cell is not a barred cell. (2) The cell fulfills the cellselection criteria.

“Barred cell” is shown in the system information. “Reserved cell” isshown in the system information.

“Camping on a cell” represents the state where a UE has completed thecell selection/reselection process and the UE has selected a cell formonitoring the system information and paging information.

Base stations referred to as Home-NodeB (Home-NB; HNB) and Home-eNodeB(Home-eNB; HeNB) are studied in 3GPP. HNB/HeNB is a base station for,for example, household, corporation or commercial access service inUTRAN/E-UTRAN. Non-Patent Document 4 discloses three different modes ofthe access to the HeNB and HNB. Specifically, those are an open accessmode, a closed access mode and a hybrid access mode.

The respective modes have the following characteristics. In the openaccess mode, the HeNB and HNB are operated as a normal cell of a normaloperator. In the closed access mode, the HeNB and HNB are operated as aCSG cell. The CSG cell is a cell where only CSG members are allowedaccess. In the hybrid access mode, non-CSG members are allowed access atthe same time. In other words, a cell in the hybrid access mode (alsoreferred to as hybrid cell) is the cell that supports both the openaccess mode and the closed access mode.

In 3GPP, there is a range of PCIs in all physical cell identities(PCIs), which is reserved by the network for use by CSG cells (seeChapter 10.5.1.1 of Non-Patent Document 1). Splitting the range of PCIsis referred to PCI-split as times. The PCI split information isbroadcast in the system information from the base station to the userequipments being served thereby. Non-Patent Document 5 discloses thebasic operation of a user equipment using PCI split. The user equipmentthat does not have the PCI split information needs to perform cellsearch using all PCIs (for example, using all 504 codes). On the otherhand, the user equipment that has the PCI split information is capableof performing cell search using the PCI split information.

Further, specifications standard of long term evolution advanced (LTE-A)as Release 10 are pursued in 3GPP (see Non-Patent Document 6 andNon-Patent Document 7).

As to the LTE-A system, it is studied that a relay (relay node (RN)) issupported for achieving a high data rate, high cell-edge throughput, newcoverage area, and the like. The relay node is wirelessly connected tothe radio-access network via a donor cell (Donor eNB; DeNB). The network(NW)-to-relay node link shares the same frequency band with thenetwork-to-UE link within the range of the donor cell. In this case, theUE in Release 8 can also be connected to the donor cell. The linkbetween a donor cell and a relay node is referred to as a backhaul link,and the link between the relay node and the UE is referred to as anaccess link.

As multiplexing of a backhaul link in frequency division duplex (FDD),the transmission from DeNB to RN is carried out in a downlink (DL)frequency band, and the transmission from RN to DeNB is carried out inan uplink (UL) frequency band. As multiplexing of resources in relays, alink from DeNB to RN and a link from RN to UE are time-divisionmultiplexed in one frequency band, and a link from RN to DeNB and a linkfrom UE to RN are also time-division multiplexed in one frequency band.This enables to prevent, in a relay, the transmission of the relay frominterfering with the reception of the own relay.

Not only a normal eNB (macro cell) but also so-called local nodes suchas pico eNB (pico cell), HeNB/HNB/CSG cell, node for hotzone cells,relay node, and remote radio head (RRH) are studied in 3GPP.

The frequency bands (hereinafter, referred to as “operating bands” insome cases) usable for communication have been predetermined in the LTE.Non-Patent Document 8 describes the frequency bands. In the frequencydivision duplex (FDD) communication, a frequency band for downlink(hereinafter, referred to as “downlink frequency band” in some cases)and a frequency band for uplink (hereinafter, referred to as “uplinkfrequency band” in some cases) that is paired with the downlinkfrequency band have been predetermined, where the uplink frequency banddiffers from the downlink frequency band. This is because the downlinkand uplink are necessarily required for conventional communication suchas voice communication so that transmission and reception are enabled atthe same time by splitting the frequencies between downlink and uplinkin the FDD.

In the FDD, a default value of an interval (TX-RX frequency separation)between a carrier frequency of resources for use in downlink(hereinafter, referred to as “downlink carrier frequency” in some cases)and a carrier frequency of resources for use in uplink (hereinafter,referred to as “uplink carrier frequency” in some cases) is determinedper frequency band. Non-Patent Document 8 describes a default value atthe TX-RX frequency separation.

In the LTE, a cell broadcasts, to UEs being served thereby, thefrequency band information and uplink carrier frequency deployed by theown cell as broadcast information. Specifically, the frequency bandinformation is included in the SIB 1. The uplink carrier frequency isincluded in the SIB2. In a case where the uplink carrier frequency isnot included in the SIB2, the uplink carrier frequency is derived fromthe downlink carrier frequency using the default value at the TX-RXfrequency separation. The UE is capable of recognizing the downlinkcarrier frequency through cell selection or reselection and is capableof obtaining the frequency band and uplink carrier frequency deployed bythe cell the through reception of the broadcast information from thecell.

As disclosed in Non-Patent Document 1, the development of “long termevolution advanced (LTE-A)” specifications as Release 10 is pursued in3GPP.

Carrier aggregation (CA) is studied in the LTE-A system, in which two ormore component carriers (CCs) are aggregated to support widertransmission bandwidths up to 100 MHz.

A Release 8 or 9-compliant UE, which supports LTE, is capable oftransmission and reception on only the CC corresponding to one servingcell. On the other hand, it is conceivable that a Release 10-compliantUE may have the capability of transmission and reception, onlyreception, or only transmission on the CCs corresponding to a pluralityof serving cells at the same time.

Each CC employs the configuration of Release 8 or 9, and the CA supportscontiguous CCs, non-contiguous CCs, and CCs in different frequencybandwidths. The UE cannot configure the number of uplink CCs (UL CCs)equal to or more than the number of downlink CCs (DL CCs). The CCsconfigured by the same eNBs do not need to provide the same coverage.The CC is compatible with Release 8 or 9.

In CA, an independent HARQ entity is provided per serving cell in uplinkas well as downlink. A transport block is generated per TTI for eachserving cell. Each transport block and HARQ retransmission are mapped toa single serving cell.

In a case where CA is configured, a UE has single RRC connection with aNW. In RRC connection, one serving cell provides NAS mobilityinformation and security input. This cell is referred to as primary cell(PCell). In downlink, a carrier corresponding to Pcell is a downlinkprimary component carrier (DL PCC). In uplink, a carrier correspondingto Pcell is an uplink primary component carrier (UL PCC). A secondarycell (SCell) is configured to form a pair of a PCell and a serving cell,in accordance with the UE capability. In downlink, a carriercorresponding to SCell is a downlink secondary component carrier (DLSCC). In uplink, a carrier corresponding to SCell is an uplink secondarycomponent carrier (UL SCC).

A pair of one PCell and a serving cell configured by one or more SCellsis configured for one UE.

In each SCell, a UE is capable of using resources for uplink (UL) inaddition to resources for downlink (DL). The number of DL SCCs is equalto or more than the number of UL SCCs. No SCell is used for onlyresources for UL. Each resource for UL belongs to only one serving cellfor one UE. The number of serving cells depends on the UE capability.

The PCell is changed through only a HO procedure. The PCell is used fortransmission of PUCCH. The PUCCH for HARQ of the DL-SCH without UL-SCHis transmitted through only UL PCC. Differently from Scells, the PCellis not de-activated.

Re-establishment is triggered when the PCell results in a radio linkfailure (RLF). Re-establishment is not triggered in a case of SCells.The NAS information is obtained from the PCell.

The SCells are reconfigured, added, or removed through RRC. Also inhandover within the LTE, the SCells used together with a target PCellare added, removed, or reconfigured through RRC.

In a case of adding a SCell, dedicated RRC signaling is used to transmitthe all system information (SI) required for the SCell. That is,addition is performed in a connected mode, and the UE does not have toreceive the SI broadcast from the SCell.

In each cell, SIB2 represents a carrier frequency of a resource foruplink.

PRIOR ART DOCUMENTS Non-Patent Documents

-   Non-Patent Document 1: 3GPP TS 36.300 V10.1.0-   Non-Patent Document 2: 3GPP TS 36.331 V9.4.0-   Non-Patent Document 3: 3GPP TS 36.304 V9.4.0 Chapter 3.1, Chapter    4.3, Chapter 5.2.4-   Non-Patent Document 4: 3GPP S1-083461-   Non-Patent Document 5: 3GPP R2-082899-   Non-Patent Document 6: 3GPP TR 36.814 V9.0.0-   Non-Patent Document 7: 3GPP TR 36.912 V9.3.0-   Non-Patent Document 8: 3GPP TS 36.101 V10.0.0

SUMMARY OF INVENTION Problem to be Solved by the Invention

It is considered that the LTE-A system supports frequency bandwidthslarger than frequency bandwidths of the LTE system, specifically,frequency bandwidths up to 100 MHz for improving a data rate. Frequencyresources are used in various situations in areas. Therefore, it isconceivable that the 100 MHz of frequency bandwidth cannot be securedcontinuously in some areas. In other words, only discrete andnarrow-band frequency resources can be secured at times. Also in such acase, flexible frequency band allocation is highly demanded foreffectively using frequency resources. Meanwhile, differently from theconventional voice communication service, the service that requiresdifferent frequency bandwidths between DL and UL is highly demanded.

However, in a conventional communication system, resources for UL arerequired to be necessarily reserved in the same frequency band as thatof the resources for DL in a conventional communication system, whichinterferes with efficient use of frequency resources. In addition, it isnecessarily required to reserve, in the frequency band for downlink, thefrequency band for uplink which is paired therewith. Therefore, in acase where, for example, a large number of free discrete and narrowfrequency bands exist, it is difficult to use those. This leads to aproblem of decreased use efficiency of frequency resources.

An object of the present invention is to provide a base station deviceand a communication system allowing flexible use of frequency resourcesand capable of improving use efficiency of frequency resources whileincreasing a data rate.

Means to Solve the Problem

A base station device of the present invention performs radiocommunication with a communication terminal device, wherein: the basestation device configures a non-associated cell that includes a resourcefor downlink and does not include a resource for uplink, the resourcefor downlink being allocated to downlink communication to thecommunication terminal device, the resource for uplink being allocatedto uplink communication from the communication terminal device; the basestation device notifies the communication terminal device of linkinformation indicating that the non-associated cell does not include theresource for uplink, using the resource for downlink; and the basestation device communicates with the communication terminal device usingthe non-associated cell.

Further, a base station device of the present invention performs radiocommunication with a communication terminal device, wherein: the basestation device configures an asymmetrical cell including a resource fordownlink and a resource for uplink, the resource for downlink beingallocated to downlink communication to the communication terminaldevice, the resource for uplink being included in a frequency banddifferent from that of the resource for downlink and being allocated touplink communication from the communication terminal device; the basestation device notifies the communication terminal device of resourceinformation for uplink regarding the resource for uplink using theresource for downlink; and the base station device communicates with thecommunication terminal device using the asymmetrical cell.

Further, a base station device of the present invention performs radiocommunication with a communication terminal device, wherein: the basestation device configures a non-associated cell that includes a resourcefor uplink and does not include a resource for downlink, the resourcefor uplink being allocated to uplink communication from thecommunication terminal device, the resource for downlink being allocatedto downlink communication to the communication terminal device; and thebase station device communicates with the communication terminal deviceusing the non-associated cell.

Further, a base station device of the present invention performs radiocommunication with a communication terminal device, wherein: the basestation device configures a frequency band for downlink that includes aresource for downlink and does not include a resource for uplink, theresource for downlink being allocated to downlink communication to thecommunication terminal device, the resource for uplink being allocatedto uplink communication from the communication terminal device; and thebase station device communicates with the communication terminal deviceusing the frequency band for downlink.

Further, a base station device of the present invention performs radiocommunication with a communication terminal device, wherein: the basestation device configures a frequency band for uplink that includes aresource for uplink and does not include a resource for downlink, theresource for uplink being allocated to uplink communication from thecommunication terminal device, the resource for downlink being allocatedto downlink communication to the communication terminal device; and thebase station device communicates with the communication terminal deviceusing the frequency band for uplink.

Further, a communication system of the present invention includes thebase station device and a communication terminal device being able toperform radio communication with the base station device.

Effects of the Invention

According to the base station device of the present invention, it ispossible to flexibly use frequency resources and improve the useefficiency of frequency resources while increasing a data rate.

According to the communication system of the present invention, it ispossible to flexibly use frequency resources and improve the useefficiency of frequency resources while increasing a data rate.

These and other objects, features, aspects and advantages of the presentinvention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating the configuration of an LTEcommunication system.

FIG. 2 is a diagram illustrating the configuration of a radio frame usedin the LTE communication system.

FIG. 3 is a diagram illustrating the configuration of an MBSFN frame.

FIG. 4 is a diagram illustrating physical channels used in the LTEcommunication system.

FIG. 5 is a diagram illustrating transport channels used in the LTEcommunication system.

FIG. 6 is a diagram illustrating logical channels used in the LTEcommunication system.

FIG. 7 is a block diagram showing the overall configuration of an LTEmobile communication system currently under discussion of 3GPP.

FIG. 8 is a block diagram showing the configuration of a user equipment(user equipment 71 of FIG. 7) according to the present invention.

FIG. 9 is a block diagram showing the configuration of a base station(base station 72 of FIG. 7) according to the present invention.

FIG. 10 is a block diagram showing the configuration of an MME (MME unit73 of FIG. 7) according to the present invention.

FIG. 11 is a block diagram showing the configuration of a HeNBGW 74shown in FIG. 7 that is a HeNBGW according to the present invention.

FIG. 12 is a flowchart showing an outline from a cell search to an idlestate operation performed by a user equipment (UE) in the LTEcommunication system.

FIG. 13 is a diagram showing the concept of CA.

FIG. 14 is a diagram showing the configuration in which one UL CC isassociated with one DL CC.

FIG. 15 is a diagram showing the configuration in which the same UL CCis associated with two different DL CCs.

FIG. 16 is a diagram showing the configuration in which a UL CC in afrequency band different from a corresponding predetermined frequencyband of uplink is associated with a DL CC in a frequency band of somedownlink.

FIG. 17 is a diagram showing the configuration in which a UL CC is notassociated with a DL CC.

FIG. 18 is a diagram showing the concept of a cell configured by a DL/ULlink via SIB2.

FIG. 19 is a diagram showing a cell configured by only a DL CC without aUL CC to be associated with the DL CC.

FIG. 20 is a flowchart showing a procedure by an eNB regarding theprocess of setting the system information (SI) of a cell in a case wherethe DL/UL link information of the cell is used.

FIG. 21 is a flowchart showing a procedure by a UE regarding the processof prohibiting a UE from selecting, reselecting, or camping on a cell inwhich a UL CC is not configured in a case where the DL/UL linkinformation of the cell is used.

FIG. 22 is a flowchart showing a procedure by an eNB regarding theprocess of setting the system information (SI) of the cell in a casewhere the cell barred information is used.

FIG. 23 is a flowchart showing a procedure by a UE regarding the processof prohibiting a UE from selecting, reselecting, or camping on a cell inwhich a UL CC is not configured in a case where the cell barredinformation is used.

FIG. 24 is a flowchart showing a procedure by an eNB regarding theprocess of setting the system information (SI) of a cell in a case whereuplink access is prohibited using the DL/UL link information.

FIG. 25 is a flowchart showing a procedure by a UE regarding the processof prohibiting a UE from performing uplink access in a cell, in which aUL CC is not configured, using DL/UL link information of the cell.

FIG. 26 is a flowchart showing a procedure by an eNB regarding theprocess of setting the system information (SI) of a cell in a case wherethe information for stochastically prohibiting access is used.

FIG. 27 is a flowchart showing a procedure by a UE regarding the processof prohibiting a UE from performing uplink access in a cell in which aUL CC is not configured in a case where the information forstochastically prohibiting access is used.

FIG. 28 is a diagram for describing cells for use in CA in a firstembodiment of the present invention.

FIG. 29 is a diagram showing an example of a sequence of CA in a casewhere a cell in which a UL CC is not configured is used.

FIG. 30 is a diagram showing a cell in which a UL CC to be associatedwith a DL CC is configured in a different frequency band.

FIG. 31 is a flowchart showing a procedure by an eNB regarding theprocess of setting the system information (SI) of a cell.

FIG. 32 is a flowchart showing a procedure by a UE in a case where acell in which a DL CC and a UL CC are configured in different frequencybands is selected.

FIG. 33 is a flowchart showing a procedure by an eNB regarding theprocess of setting the system information (SI) of a cell in a case wherethe cell barred information is used.

FIG. 34 is a flowchart showing a procedure by a UE regarding the processof prohibiting a UE from selecting, reselecting, or camping on a cell inwhich a UL CC is configured in a frequency band different from that of aDL CC in a case where the cell barred information is used.

FIG. 35 is a diagram for describing cells for use in CA in a secondembodiment of the present invention.

FIG. 36 is a diagram showing an example of a sequence of CA in a casewhere a cell in which a DL CC and a UL CC are configured in differentfrequency bands is used.

FIG. 37 is a diagram showing the concept of two cells which areconfigured by associating the same UL CC with two DL CCs in differentfrequency bands.

FIG. 38 is a diagram showing an example of a sequence of CA in a casewhere two cells are configured by associating the same UL CC with two DLCCs in different frequency bands.

FIG. 39 is a diagram showing another example of the sequence of CA inthe case where two cells are configured by associating the same UL CCwith two DL CCs in different frequency bands.

FIG. 40 is a diagram showing the concept of a frequency band configuredby one or more resources for DL without a resource for UL to beassociated therewith.

FIG. 41 is a diagram showing a setting example of a frequency bandconfigured by one or more resources for DL without a resource for UL tobe associated therewith.

FIG. 42 is a diagram showing the concept of a cell configured by only aUL CC without a DL CC to be associated with the UL CC.

FIG. 43 is a diagram for describing cells for use in CA in a fourthembodiment of the present invention.

FIG. 44 is a diagram showing an example of a sequence of CA in a casewhere a cell in which a DL CC is not configured is used.

FIG. 45 is a diagram showing the concept of a frequency band configuredby one or more resources for UL without resources for DL to beassociated therewith.

FIG. 46 is a diagram showing a setting example of a frequency bandconfigured by one or more resources for UL without a resource for DL tobe associated therewith.

EMBODIMENTS FOR CARRYING OUT THE INVENTION First Embodiment

FIG. 7 is a block diagram showing an overall configuration of an LTEmobile communication system, which is currently under discussion of3GPP. Currently, an overall system configuration including closedsubscriber group (CSG) cells (Home-eNodeBs (Home-eNB; HeNB) of E-UTRAN,Home-NB (HNB) of UTRAN) and non-CSG cells (eNodeB (eNB) of E-UTRAN,NodeB (NB) of UTRAN, and BSS of GERAN) is studied in 3GPP and, as toE-UTRAN, the configuration as shown in FIG. 7 is proposed (see Chapter4.6.1 of Non-Patent Document 1).

FIG. 7 is described. A user terminal device (hereinafter, referred to as“user equipment” or “UE”) 71 is capable of performing radiocommunication with a base station device (hereinafter, referred to as“base station”) 72 and transmits/receives signals through radiocommunication. The user terminal device is equivalent to a communicationterminal device. The base stations 72 are classified into an eNB 72-1that is a macro cell and a Home-eNB 72-2 that is a local node. The eNB72-1 is equivalent to a large-scale base station device and has arelatively large-scale coverage as the coverage in a range in whichcommunication is allowed with the user equipment UE 71. The Home-eNB72-2 is equivalent to a small-scale base station device and has arelatively small-scale coverage as the coverage.

The eNB 72-1 is connected to an MME/S-GW unit (hereinafter, referred toas an “MME unit” in some cases) 73 including an MME, S-GW or MME andS-GW through an S1 interface, and control information is communicatedbetween the eNB 72-1 and the MME unit 73. A plurality of MME units 73may be connected to one eNB 72-1. The eNBs 72-1 are connected to eachother by means of an X2 interface, and control information iscommunicated between the eNBs 72-1.

The Home-eNB 72-2 is connected to the MME unit 73 by means of an S1interface, and control information is communicated between the Home-eNB72-2 and the MME unit 73. A plurality of Home-eNBs 72-2 are connected toone MME unit 73. Also, the Home-eNBs 72-2 are connected to the MME units73 through a Home-eNB Gateway (HeNBGW) 74. The Home-eNBs 72-2 areconnected to the HeNBGW 74 by means of the S1 interface, and the HeNBGW74 is connected to the MME units 73 through an S1 interface. One or aplurality of Home-eNBs 72-2 are connected to one HeNBGW 74, andinformation is communicated therebetween through an S1 interface. TheHeNBGW 74 is connected to one or a plurality of MME units 73, andinformation is communicated therebetween through an S1 interface.

Further, the configuration below is currently studied in 3GPP. The X2interface between the Home-eNBs 72-2 is not supported. The HeNBGW 74appears to the MME unit 73 as the eNB 72-1. The HeNBGW 74 appears to theHome-eNB 72-2 as the MME unit 73. The interfaces between the Home-eNBs72-2 and the MME units 73 are the same, which are the S1 interfaces,irrespective of whether or not the Home-eNB 72-2 is connected to the MMEunit 73 through the HeNBGW 74. The mobility to the Home-eNB 72-2 or themobility from the Home-eNB 72-2 that spans the plurality of MME units 73is not supported. The Home-eNB 72-2 supports a single cell.

FIG. 8 is a block diagram showing the configuration of the userequipment (user equipment 71 of FIG. 7) according to the presentinvention. The transmission process of the user equipment 71 shown inFIG. 8 is described. First, a transmission data buffer unit 803 storesthe control data from a protocol processing unit 801 and the user datafrom an application unit 802. The data stored in the transmission databuffer unit 803 is transmitted to an encoding unit 804 and is subjectedto an encoding process such as error correction. There may exist thedata output from the transmission data buffer unit 803 directly to amodulating unit 805 without the encoding process. The data encoded bythe encoding unit 804 is modulated by the modulating unit 805. Themodulated data is output to a frequency converting unit 806 after beingconverted into a baseband signal, and then is converted into a radiotransmission frequency. After that, a transmission signal is transmittedfrom an antenna 807 to the base station 72.

The user equipment 71 executes the reception process as follows. Theradio signal is received through the antenna 807 from the base station72. The received signal is converted from a radio reception frequency toa baseband signal by the frequency converting unit 806 and is thendemodulated by a demodulating unit 808. The demodulated data istransmitted to a decoding unit 809 and is subjected to a decodingprocess such as error correction. Among the pieces of decoded data, thecontrol data is transmitted to the protocol processing unit 801, whilethe user data is transmitted to the application unit 802. A series ofprocesses of the user equipment 71 is controlled by a control unit 810.This means that, though not shown in FIG. 8, the control unit 810 isconnected to the respective units 801 to 809.

FIG. 9 is a block diagram showing the configuration of the base station(base station 72 of FIG. 7) according to the present invention. Thetransmission process of the base station 72 shown in FIG. 9 isdescribed. An EPC communication unit 901 performs datatransmission/reception between the base station 72 and the EPCs (such asMME unit 73 and HeNBGW 74). A communication with another base stationunit 902 performs data transmission/reception to/from another basestation. The X2 interface between the Home-eNBs 72-2 is not intended tobe supported, and accordingly, it is conceivable that the communicationwith another base station unit 902 may not exist in the Home-eNB 72-2.The EPC communication unit 901 and the communication with another basestation unit 902 respectively transmit/receive information to/from aprotocol processing unit 903. The control data from the protocolprocessing unit 903, and the user data and control data from the EPCcommunication unit 901 and the communication with another base stationunit 902 are stored in a transmission data buffer unit 904.

The data stored in the transmission data buffer unit 904 is transmittedto an encoding unit 905 and is then subjected to an encoding processsuch as error correction. There may exist the data output from thetransmission data buffer unit 904 directly to a modulating unit 906without the encoding process. The encoded data is modulated by themodulating unit 906. The modulated data is output to a frequencyconverting unit 907 after being converted into a baseband signal, and isthen converted into a radio transmission frequency. After that, atransmission signal is transmitted from an antenna 908 to one or aplurality of user equipments 71.

While, the reception process of the base station 72 is executed asfollows. A radio signal from one or a plurality of user equipments 71 isreceived through the antenna 908. The received signal is converted froma radio reception frequency into a baseband signal by the frequencyconverting unit 907, and is then demodulated by a demodulating unit 909.The demodulated data is transmitted to a decoding unit 910 and is thensubjected to a decoding process such as error correction. Among thepieces of decoded data, the control data is transmitted to the protocolprocessing unit 903, EPC communication unit 901, or communication withanother base station unit 902, while the user data is transmitted to theEPC communication unit 901 and the communication with another basestation unit 902. A series of processes by the base station 72 iscontrolled by a control unit 911. This means that, though not shown inFIG. 9, the control unit 911 is connected to the respective units 901 to910.

The functions of the Home-eNB 72-2 currently under discussion of 3GPPare described below (see Chapter 4.6.2 of Non-Patent Document 1). TheHome-eNB 72-2 has the same function as that of the eNB 72-1. Inaddition, the Home-eNB 72-2 has the function of discovering a suitableserving HeNBGW 74 in a case of connection to the HeNBGW 74. The Home-eNB72-2 is connected only to one HeNBGW 74. That is, in a case of theconnection to the HeNBGW 74, the Home-eNB 72-2 does not use the Flexfunction in the S1 interface. When the Home-eNB 72-2 is connected to oneHeNBGW 74, it is not simultaneously connected to another HeNBGW 74 oranother MME unit 73.

The TAC and PLMN ID of the Home-eNB 72-2 are supported by the HeNBGW 74.When the Home-eNB 72-2 is connected to the HeNBGW 74, selection of theMME unit 73 at “UE attachment” is performed by the HeNBGW 74 instead ofthe Home-eNB 72-2. The Home-eNB 72-2 may be deployed without networkplanning. In this case, the Home-eNB 72-2 is moved from one geographicalarea to another geographical area. Accordingly, the Home-eNB 72-2 inthis case is required to be connected to a different HeNBGW 74 dependingon its location.

FIG. 10 is a block diagram showing the configuration of the MMEaccording to the present invention. FIG. 10 shows the configuration ofan MME 73 a included in the MME unit 73 shown in FIG. 7 described above.A PDN GW communication unit 1001 performs data transmission/receptionbetween the MME 73 a and a PDN GW. A base station communication unit1002 performs data transmission/reception between the MME 73 a and thebase station 72 by means of the S1 interface. In the case where the datareceived from the PDN GW is user data, the user data is transmitted fromthe PDN GW communication unit 1001 to the base station communicationunit 1002 through a user plane communication unit 1003 and is thentransmitted to one or a plurality of base stations 72. In the case wherethe data received from the base station 72 is user data, the user datais transmitted from the base station communication unit 1002 to the PDNGW communication unit 1001 through the user plane communication unit1003 and is then transmitted to the PDN GW.

In the case where the data received from the PDN GW is control data, thecontrol data is transmitted from the PDN GW communication unit 1001 to acontrol plane control unit 1005. In the case where the data receivedfrom the base station 72 is control data, the control data istransmitted from the base station communication unit 1002 to the controlplane control unit 1005.

A HeNBGW communication unit 1004 is provided in the case where theHeNBGW 74 is provided, which performs data transmission/reception bymeans of the interface (IF) between the MME 73 a and the HeNBGW 74according to an information type. The control data received from theHeNBGW communication unit 1004 is transmitted from the HeNBGWcommunication unit 1004 to the control plane control unit 1005. Theprocessing results of the control plane control unit 1005 aretransmitted to the PDN GW through the PDN GW communication unit 1001.The processing results of the control plane control unit 1005 aretransmitted to one or a plurality of base stations 72 by means of the S1interface through the base station communication unit 1002, and aretransmitted to one or a plurality of HeNBGWs 74 through the HeNBGWcommunication unit 1004.

The control plane control unit 1005 includes an NAS security unit1005-1, an SAE bearer control unit 1005-2, and an idle state mobilitymanaging unit 1005-3, and performs overall process for the controlplane. The NAS security unit 1005-1 provides, for example, security of anon-access stratum (NAS) message. The SAE bearer control unit 1005-2manages, for example, a system architecture evolution (SAE) bearer. Theidle state mobility managing unit 1005-3 performs, for example, mobilitymanagement of an idle state (LTE-IDLE state, which is merely referred toas idle as well), generation and control of paging signal in an idlestate, addition, deletion, update, and search of a tracking area (TA) ofone or a plurality of user equipments 71 being served thereby, andtracking area list (TA list) management.

The MME 73 a begins a paging protocol by transmitting a paging messageto the cell belonging to a tracking area (TA) in which the UE isregistered. The idle state mobility managing unit 1005-3 may manage theCSG of the Home-eNBs 72-2 to be connected to the MME 73 a, CSG-IDs, anda whitelist.

In the CSG-ID management, the relationship between a user equipmentcorresponding to the CSG-ID and the CSG cell is managed (added, deleted,updated or searched). For example, it may be the relationship betweenone or a plurality of user equipments whose user access registration hasbeen performed with a CSG-ID and the CSG cells belonging to this CSG-ID.In the whitelist management, the relationship between the user equipmentand the CSG-ID is managed (added, deleted, updated, or searched). Forexample, one or a plurality of CSG-IDs with which user registration hasbeen performed by a user equipment may be stored in the whitelist. Theabove-mentioned management related to the CSG may be performed byanother part of the MME 73 a. A series of processes by the MME 73 a iscontrolled by a control unit 1006. This means that, though not shown inFIG. 10, the control unit 1006 is connected to the respective units 1001to 1005.

The function of the MME 73 a currently under discussion of 3GPP isdescribed below (see Chapter 4.6.2 of Non-Patent Document 1). The MME 73a performs access control for one or a plurality of user equipmentsbeing members of closed subscriber groups (CSGs). The MME 73 arecognizes the execution of paging optimization as an option.

FIG. 11 is a block diagram showing the configuration of the HeNBGW 74shown in FIG. 7 that is a HeNBGW according to the present invention. AnEPC communication unit 1101 performs data transmission/reception betweenthe HeNBGW 74 and the MME 73 a by means of the S1 interface. A basestation communication unit 1102 performs data transmission/receptionbetween the HeNBGW 74 and the Home-eNB 72-2 by means of the S1interface. A location processing unit 1103 performs the process oftransmitting, to a plurality of Home-eNBs 72-2, the registrationinformation or the like among the data transmitted from the MME 73 athrough the EPC communication unit 1101. The data processed by thelocation processing unit 1103 is transmitted to the base stationcommunication unit 1102 and is transmitted to one or a plurality ofHome-eNBs 72-2 through the S1 interface.

The data only caused to pass through (to be transparent) withoutrequiring the process by the location processing unit 1103 is passedfrom the EPC communication unit 1101 to the base station communicationunit 1102, and is transmitted to one or a plurality of Home-eNBs 72-2through the S1 interface. A series of processes by the HeNBGW 74 iscontrolled by a control unit 1104. This means that, though not shown inFIG. 11, the control unit 1104 is connected to the respective units 1101to 1103.

The function of the HeNBGW 74 currently under discussion of 3GPP isdescribed below (see Chapter 4.6.2 of Non-Patent Document 1). The HeNBGW74 relays an S1 application. The HeNBGW 74 terminates the S1 applicationthat is not linked to the user equipment 71 though it is a part of theprocedures toward the Home-eNB 72-2 and towards the MME 73 a. When theHeNBGW 74 is deployed, the procedure that is not linked to the userequipment 71 is communicated between the Home-eNB 72-2 and the HeNBGW 74and between the HeNBGW 74 and the MME 73 a. The X2 interface is not setbetween the HeNBGW 74 and another node. The HeNBGW 74 recognizes theexecution of paging optimization as an option.

Next, an example of a typical cell search method in a mobilecommunication system is described. FIG. 12 is a flowchart showing anoutline from cell search to idle state operation performed by a userequipment (UE) in the LTE communication system. When starting cellsearch, in Step ST1201, the user equipment synchronizes the slot timingand frame timing by a primary synchronization signal (P-SS) and asecondary synchronization signal (S-SS) transmitted from a neighbourbase station. Synchronization codes, which correspond to physical cellidentities (PCIs) assigned per cell one by one, are assigned to thesynchronization signals (SS) including the P-SS and S-SS. The number ofPCIs is currently studied in 504 ways, and these 504 ways are used forsynchronization, and the PCIs of the synchronized cells are detected(specified).

Next, in Step ST1202, the user equipment detects a reference signal RS(cell-specific reference signal (CRS)) transmitted from the base stationper cell and measures the received power (also referred to as RSRP). Thecode corresponding to the PCI one by one is used for the referencesignal RS, and separation from another cell is enabled by correlationusing the code. The code for RS of the cell is derived from the PCIspecified in Step ST1201, which makes it possible to detect the RS andmeasure the RS received power.

Next, in Step ST1203, the user equipment selects the cell having thebest RS reception quality (for example, cell having the highest RSreceived power, that is, best cell) from one or more cells that havebeen detected up to Step ST1202.

In Step ST1204, next, the user equipment receives the PBCH of the bestcell and obtains the BCCH that is the broadcast information. A masterinformation block (MIB) containing the cell configuration information ismapped to the BCCH over the PBCH. Accordingly, the MIB is obtained byobtaining the BCCH through reception of the PBCH. Examples of the MIBinformation include the downlink (DL) system bandwidth (also referred toas transmission bandwidth configuration (dl-bandwidth)), transmissionantenna number, and system frame number (SFN).

In Step ST1205, next, the user equipment receives the DL-SCH of the cellbased on the cell configuration information of the MIB, to therebyobtain a system information block (SIB) 1 of the broadcast informationBCCH. The SIB 1 contains the information related to the access to thecell, information related to cell selection, and scheduling informationof other SIB (SIBk; k is an integer equal to or larger than two). Inaddition, the SIB 1 contains a tracking area code (TAC).

In Step ST1206, next, the user equipment compares the TAC of the SIB1received in Step ST1205 with the TAC in the tracking area (TA) list thathas been already possessed by the user equipment. In a case where theTAC received in Step ST1205 is identical to the TAC included in the TAlist as a result of the comparison, the user equipment enters an idlestate operation in the cell. In a case where the TAC received in StepST1205 is not included in the TA list as a result of the comparison, theuser equipment requires a core network (EPC) (including MME and thelike) to change a TA through the cell for performing tracking areaupdate (TAU). The core network updates the TA list based on anidentification number (such as a UE-ID) of the user equipmenttransmitted from the user equipment together with a TAU request signal.The core network transmits the updated TA list to the user equipment.The user equipment rewrites (updates) the TAC list of the user equipmentwith the received TA list. After that, the user equipment enters theidle state operation in the cell.

In the LTE, LTE-A and universal mobile telecommunication system (UMTS),the introduction of a closed subscriber group (CSG) cell is studied. Asdescribed above, access is allowed for only one or a plurality of userequipments registered with the CSG cell. A CSG cell and one or aplurality of user equipments registered with the CSG cell constitute oneCSG. A specific identification number referred to as CSG-ID is added tothe thus constituted CSG. Note that one CSG may contain a plurality ofCSG cells. After being registered with any one of the CSG cells, theuser equipment can access another CSG cell of the CSG to which theregistered CSG cell belongs.

Alternatively, the Home-eNB in the LTE or the Home-NB in the UMTS isused as the CSG cell in some cases. The user equipment registered withthe CSG cell has a whitelist. Specifically, the whitelist is stored inthe subscriber identity module (SIM)/USIM. The CSG information of theCSG cell with which the user equipment has been registered is stored inthe whitelist. Specific examples of the CSG information include CSG-ID,tracking area identity (TAI) and TAC. Any one of the CSG-ID and TAC isadequate as long as they are associated with each other. Alternatively,GCI is adequate as long as the CSG-ID and TAC are associated with globalcell identity (GCI).

As can be seen from the above, the user equipment that does not have awhitelist (including a case where the whitelist is empty in the presentinvention) is not allowed to access the CSG cell but is allowed toaccess the non-CSG cell only. On the other hand, the user equipmentwhich has a whitelist is allowed to access the CSG cell of the CSG-IDwith which registration has been performed as well as the non-CSG cell.

All physical cell identities (PCIs) are split into ones reserved for CSGcells and the others reserved for non-CSG cells is discussed in 3GPP(see Non-Patent Document 1). There is a range of PCIs in all physicalcell identities (PCIs), which is reserved by the network for use by CSGcells (see Chapter 10.5.1.1 of Non-Patent Document 1). Splitting therange of PCIs is referred to PCI-split as times. The PCI splitinformation is broadcast in the system information from the base stationto the user equipments being served thereby. Non-Patent Document 5discloses the basic operation of a user equipment by PCI split. The userequipment that does not have the PCI split information needs to performcell search using all PCIs (for example, using all 504 codes). On theother hand, the user equipment that has the PCI split information iscapable of performing cell search using the PCI split information.

Further, it has been determined that the PCIs for hybrid cells are notcontained in the PCI range for CSG cells in 3GPP (see Chapter 10.7 ofNon-Patent Document 1).

In 3GPP, there are two modes in the method of selecting or reselecting aCSG cell by a user equipment. One is an automatic mode. The feature ofthe automatic mode is described below. The user equipment performsselection or reselection with the use of an allowed CSG list (allowedCSG ID list) in the user equipment. After the completion of PLMNselection, the user equipment camps on one cell in the selected PLMNonly in a case of a non-CSG cell or a CSG cell with a CSG ID present inthe allowed CSG list. The user equipment disables an autonomous searchfunction of the CSG cell if the allowed CSG list of the user equipmentis empty (see Chapter 5.2.4.8.1 of Non-Patent Document 3).

The second is a manual mode. The feature of the manual mode is describedbelow. The user equipment shows a list of available CSGs in thecurrently selected PLMN to a user. The list of CSGs provided to the userby the user equipment is not limited to the CSGs included in the allowedCSG list stored in the user equipment. The user selects the CSG based onthe list of CSGs, and then the user equipment camps on the cell with theselected CSG ID, to thereby attempt registration (see Non-PatentDocument 3).

The HeNB and HNB are required to support various services. For example,an operator causes the predetermined HeNB and HNB to register userequipments therein and permits only the registered user equipments toaccess the cells of the HeNB and HNB, which increases radio resourcesavailable for the user equipments and enables high-speed communication.In such a service, the operator correspondingly sets a higher accountingfee compared with a normal service.

In order to achieve the above-mentioned service, the closed subscribergroup cell (CSG cell) accessible only to the registered (subscribed ormember) user equipments is introduced. It is required to install a largenumber of closed subscriber group cells (CSG cells) in shopping malls,apartment buildings, schools, companies and the like. For example, thefollowing manner of use is required; the CSG cells are installed foreach store in shopping malls, for each room in apartment buildings, foreach classroom in schools, and for each section in companies such thatonly the users who have registered with the respective CSG cells arepermitted to use those CSG cells. The HeNB/HNB is required not only tocomplement the communication outside the coverage of the macro cell butalso to support various services as described above. This also leads toa case where the HeNB/HNB is installed within the coverage of the macrocell.

As described above, as to the LTE-A system, CA for aggregating two ormore CCs is studied to support the frequency bandwidths up to 100 MHzwider than the frequency bandwidth of the LTE system.

FIG. 13 is a diagram showing the concept of CA. An eNB shown in FIG. 13configures a cell n configured by a DL CCn and a UL CCn which isassociated with the DL CCn by a DL/UL link via SIB2. The carrierfrequency of the DL CCn is denoted by Fn (DL), and the carrier frequencyof the UL CCn is denoted by Fn (UL). Here, n is an integer of one tofive.

A UE camps on the cell1 and performs RRC connection indicated by anarrow 1301. As a result, the cell1 becomes a PCell.

After that, the eNB notifies the UE of the information regarding the CCsto be aggregated through dedicated RRC signaling indicated by an arrow1302. The information regarding a cell m configured by a DL CCm and a ULCCm, for example, system information is notified as the informationregarding the CCs. Here, m is an integer of two to five. The eNBnotifies the UE of the information regarding the CCs in this manner,whereby the cell2 to the cell5 become SCells.

As described above, the eNB performs CA for the UE with the cell1 to thecell5. Then, the UE performs communication with the cell1 to the cell5based on CA, as indicated by an arrow 1303.

A configuration example of a UE that supports CA is described. Itsuffices that in the configuration shown in FIG. 8 described above, apart or the whole of the modulating unit 805, frequency converting unit806, antenna 807, and demodulating unit 808 is caused to support a widerbandwidth. In the transmitter, a part or the whole of the modulatingunit 805, frequency converting unit 806, and antenna 807 may be causedto operate in a band including a predetermined number of contiguous ULCCs. In the receiver, a part or the whole of the antenna 807, frequencyconverting unit 806, and demodulating unit 808 may be caused to operatein a band including a predetermined number of contiguous DL CCs. Thisenables to support CA by a predetermined number of contiguous UL CCs orDL CCs.

As another method, it suffices that a plurality of a part or the wholeof the modulating unit 805, frequency converting unit 806, antenna 807,and demodulating unit 808 are provided in parallel to operate in a bandincluding a predetermined number of non-contiguous UL CCs or DL CCs. Inthe transmitter, a plurality of a part or the whole of the modulatingunit 805, frequency converting unit 806, and antenna 807 may be providedin parallel so as to operate in a band including a predetermined numberof non-contiguous UL CCs. In the receiver, a plurality of a part or thewhole of the antenna 807, frequency converting unit 806, anddemodulating unit 808 may be provided in parallel so as to operate in aband including a predetermined number of non-contiguous DL CCs. Thisenables to support CA with a predetermined number of non-contiguous ULCCs or DL CCs. Alternatively, the two configurations described above maybe appropriately combined.

A configuration example of an eNB that supports CA is described. Itsuffices that in the configuration shown in FIG. 9 described above, theprotocol processing unit 903 performs the process for a UE for which CAis performed per cell configured by an eNB, and the transmission databuffer unit 904, encoding unit 905, modulating unit 906, frequencyconverting unit 907, antenna 908, demodulating unit 909, and decodingunit 910 are configured per cell. This enables to perform CA for a UE bycells configured by an eNB.

Examples of the method of associating each DL CC to be aggregated in CAand a UL CC that is paired with each DL CC with each other (hereinafter,referred to as “DL/UL link” at times) include the following two methods;one is DL/UL link via SIB2, and the other is DL/UL link performed whenthe SCell is configured through dedicated RRC signaling.

The DL/UL link through dedicated RRC signaling may differ from the DL/ULlink via SIB2 is discussed in 3GPP. For example, R2-104480 (hereinafter,referred to as “Non-Patent Document 9”) by 3GPP describes the discussionon DL/UL of a cell by 3GPP.

The DL/UL link via SIB2 is the same as the DL/UL link via SIB2 in theconventional LTE, and the carrier frequency of the UL CC is broadcast toUEs being served by each cell over the SIB2 of the DL CC of each cell.This is provided for configuring a resource for DL of a cell and aresource for UL that is paired therewith, and is thus referred to asDL/UL link specific to a cell (cell specific link) or DL/UL link of acell (cell DL/UL link).

The frequency band for downlink and the frequency band for uplink thatis paired therewith are predetermined, and thus, the DL/UL link via SIB2is performed in a frequency band for the pair.

Note that description below is not limited to the case of CA, where aresource for DL and a resource for UL are referred to as “DL CC” and “ULCC”, respectively.

Next, FIG. 14 and FIG. 15 show configuration examples of the DL/UL linkvia SIB2.

FIG. 14 is a diagram showing the configuration in which one UL CC isassociated with one DL CC. The carrier frequency of the UL CC1 is shownby the SIB2 of the DL CC1, and the carrier frequency of the UL CC2 isshown by the SIB2 of the DL CC2.

FIG. 15 is a diagram showing the configuration in which the same UL CCis associated with two different DL CCs. The carrier frequency of the ULCC1 is shown by the SIB2 of the DL CC1, and the carrier frequency of theUL CC1 is also shown by the SIB2 of the DL CC2.

Next, FIG. 16 and FIG. 17 show examples that cannot be configured by theDL/UL link via SIB2.

FIG. 16 is a diagram showing the configuration in which a UL CC in afrequency band different from a corresponding predetermined frequencyband of uplink is associated with a DL CC in a frequency band of somedownlink. In the conventional communication such as voice communication,the UL CC to be associated with the DL CC is necessarily required.Therefore, the frequency band of uplink, which is paired with thefrequency band of downlink, is predetermined in FDD for securing theconfigurations of the DL CC and UL CC. The conventional DL/UL link viaSIB2 is premised on that communication is performed in the predeterminedfrequency band for a pair, and thus, the configuration as shown in FIG.16, that is, associating to a frequency band different from apredetermined frequency band for a pair cannot be allowed. In FIG. 16,“x” represents that the configuration is not allowed by a DL/UL link viaSIB2.

FIG. 17 is a diagram showing the configuration in which the UL CC is notassociated with the DL CC. The UL CC to be associated with the DL CC isnecessarily required in the conventional communication such as voicecommunication. Therefore, it is impossible to eliminate theconfiguration as shown in FIG. 17, that is, the UL CC to be associatedwith the DL CC by the conventional DL/UL link via SIB2. In FIG. 17, “x”represents that the configuration is not allowed by a DL/UL link viaSIB2.

Meanwhile, the DL/UL link performed when the SCell is configured throughdedicated RRC signaling is introduced for carrier aggregation (CA). TheSCell is notified through dedicated RRC signaling per UE for which CA isperformed. It is premised that there is the DL/UL link via SIB2determined per cell as a system, and a link specific to a UE (UEspecific link) is configured thereon. The configuration may differbetween the DL/UL link via SIB2 and the DL/UL link through dedicated RRCsignaling is discussed in 3GPP.

Examples of the DL/UL link configured through dedicated RRC signalinginclude the same DL/UL link configuration as that of the DL/UL link viaSIB2, the configuration in which a UL CC to be associated with a DL CCis not configured, and the configuration in which a UL CC to beassociated with a DL CC differs from a UL CC of the DL/UL link via SIB2.

There is no SCell configuration that includes only a UL CC but does notinclude a DL CC to be associated with the UL CC. In addition, there isno SCell configuration in which a plurality of DL CCs are associatedwith one UL CC. Further, there is no configuration in which a frequencyband of downlink in which a DL CC is located and a UL CC in a frequencyband different from the corresponding predetermined frequency band ofuplink are associated with each other.

Allocation of flexible frequency bands is highly demanded foreffectively using frequency resources in a communication system. Inaddition, there are growing demands for the service that requiresdifferent frequency bandwidths between DL and UL, differently from theconventional voice communication service. In order to satisfy thosedemands, CA in which the number of DL CCs differs from the number of ULCCs (hereinafter, referred to as “asymmetric CA” in some cases) isdiscussed in 3GPP.

The examples of the method of enabling asymmetrical CA include a linkspecific to UE (UE specific link). This is the method of configuring aSCell different from the SIB2 link per UE and notifying the UE throughdedicated RRC signaling. This method enables, for example, theconfiguration in which a UL CC to be associated with a DL CC is notconfigured as the SCell for configuring CA. In other words, the SCellincluding only a DL CC can be configured. Accordingly, asymmetrical CAis allowed.

However, even if asymmetrical CA is allowed with the use of the DL/ULlink through dedicated RRC signaling, the DL/UL link through dedicatedRRC signaling is premised on the presence of the DL/UL link via SIB2,which results in a configuration in which a resource for UL to beassociated with a resource for DL inevitably exists per cell.Accordingly, a frequency band of downlink without a frequency band ofuplink to be paired therewith cannot be configured as a system.

Meanwhile, in the same frequency band, the same link of the resource forUL is allowed for a plurality of resources for DL by the DL/UL link viaSIB2, but the DL/UL link via SIB2 between different frequency bands isnot allowed.

FIG. 18 is a diagram showing the concept of a cell configured by theDL/UL link via SIB2. The DL CC1 and UL CC1 are configured in thefrequency band A (band A). The DL CC2 is configured in the frequencyband B (band B). In this case, the cell configured by the DL CC1 and ULCC1 located in the same frequency band, specifically, the frequency bandA, can be configured. However, the cell configured by the DL CC2 and ULCC1 located in different frequency bands, specifically, by the UL CC1located in the frequency band A and the DL CC2 located in the frequencyband B, cannot be configured. In FIG. 18, “x” represents that theconfiguration is not allowed by a DL/UL link via SIB2. Therefore, the ULCC (UL CC2) to be associated with the DL CC2 needs to be configured inthe frequency band B. That is, a UL CC needs to be necessarily providedin the same frequency band as that of the DL CC.

Therefore, even if asymmetrical CA is performed by the DL/UL linkthrough dedicated RRC signaling, the resource for UL needs to benecessarily reserved in the same frequency band as that of the resourcefor DL in a communication system, which interferes with the efficientuse of frequency resources. In addition, a frequency band for uplink,which is paired with a frequency band for downlink, needs to benecessarily reserved in the frequency band for downlink. For thisreason, in a case where, for example, there are a large number of freediscrete and narrow frequency bands, the use thereof is difficult,leading to a problem of decreased use efficiency of frequency resources.

The embodiment below discloses the method of solving the above-mentionedproblem. In the present embodiment, a cell configured by only a resourcefor DL, which does not include a resource for UL to be associated withthe resource for DL, is provided, and the information indicating thatthe resource for UL is not configured, that is, the informationindicating that the cell does not include the resource for UL isprovided as the DL/UL link information of the cell. The DL/UL linkinformation of the cell is equivalent to link information.

FIG. 19 is a diagram showing a cell configured by only a DL CC without aUL CC to be associated with the DL CC. The cell shown in FIG. 19 is acell that does not include a UL CC to be associated with the DL CC1 butincludes only a DL CC. That is, the cell shown in FIG. 19 is a cell inwhich only a resource for DL is reserved, which is equivalent to anon-associated cell.

Disclosed below is the method of associating a resource for DL and aresource for UL with each other in the present embodiment. Theinformation indicating that a UL CC is not configured is included in thesystem information as the DL/UL link information of a cell. The systeminformation may be the information of the MIB, SIB, or the like. Thecell broadcasts this information to UEs being served thereby.

In a case where the DL/UL link information of a cell is included in theMIB, the UE is capable of recognizing that a UL CC to be associated witha DL CC has not been configured by receiving the information, whichindicates that a UL CC is not configured, in the MIB to be mapped to thePBCH configured in the resource for DL of the cell. This enables the UEto recognize at an early stage that a UL CC to be associated with a DLCC has not been configured in cell selection or cell reselection.

In a case where the DL/UL link information of a cell is included in theSIB, the UE is capable of recognizing that a UL CC to be associated witha DL CC has not been configured by receiving the information, whichindicates that a UL CC is not configured, in the SIB to be mapped to thePDSCH configured in the DL CC of a cell. Accordingly, the UE can receivethe information indicating that a UL CC is not configured, together withother system information included in the SIB.

In a case where the information indicating that a UL CC is notconfigured is included in the SIB, the information may be included inthe SIB 1 or SIB2.

The SIB1 includes the frequency band information of a cell. Theinformation indicating that a UL CC is not configured is included in theSIB1 together with the frequency band information, whereby the UE iscapable of recognizing the frequency band information and theinformation indicating that a UL CC is not configured. This allows theUE to judge at an early stage whether or not camping on the cell isallowed in accordance with the capability of the own device.

The SIB2 includes the conventional DL/UL link information of a cell.Therefore, in a case where the information indicating that a UL CC isnot configured is included in the SIB2, the UE can receive theinformation indicating that a UL CC is not configured without changingthe operation of the UE to receive the SIB2 for obtaining thisinformation.

“ul-CarrierFreq” that is a parameter indicating the carrier frequency ofa UL CC to be associated with a DL CC in the SIB2 may be used. In a casewhere “ul-CarrierFreq” is used as a parameter, the following methods areused; the method in which no value is entered into the parameter, or theparameter itself is not entered into the SIB2, and the method in which aspecific value indicating that a UL CC is not configured is provided andthat value is entered.

In a case of the method in which no value is entered into a parameter,or the parameter itself is not entered into the SIB2, it is required tochange the above-mentioned limit that a default value at TX-RX frequencyseparation is used in a case where an uplink carrier frequency is notincluded in the SIB2. This is because if the above-mentioned change isnot made, it is indicated that an uplink carrier frequency is present inthe frequency away from a downlink carrier frequency by the defaultvalue. In a case where the uplink carrier frequency is not included inthe SIB2, it suffices that there is no UL CC to be associated with, orno UL CC is not configured.

In a case of the method in which a specific value indicating that no ULCC is configured is provided and that value is entered, it suffices thatthe specific value is predetermined in a static manner. For example, ina case where a value of the parameter “ul-CarrierFreq” is numbered, thespecific value is 99999. If the value of the parameter “ul-CarrierFreq”is 99999, it suffices that the configuration is made such that there isno UL CC to be associated with or no UL CC is configured. In this case,it is not required to change the above-mentioned limit that a defaultvalue at TX-RX frequency space is used in the case where the uplinkcarrier center frequency is not included in the SIB2.

The information indicating that no UL CC is configured may be theinformation indicating the presence or absence of the UL CCconfiguration. For example, the parameter indicating the presence orabsence of the UL CC configuration is “ULCCconfig”, and binaryinformation of “1” and “0” is provided. There is the UL CC configurationin the case where the value of the parameter “ULCCconfig” is “1”, whilethere is no UL CC configuration in the case where the value of theparameter “ULCCconfig” is “0”. This enables to explicitly provide thepresence or absence of the UL CC configuration to the UE.

As the information indicating that no UL CC is configured, a newparameter may be provided without using the conventional parameterindicating the carrier frequency of the UL CC to be associated with theDL CC. Alternatively, it may be predetermined that which parameters thepriority should be placed on. This enables to reduce malfunctions of aUE.

Uplink access is not allowed in a cell in which a UL CC is notconfigured. Nevertheless, in a case where a UE selects or reselects acell in which a UL CC is not configured, uplink access may be made inthis cell. In order to suppress an increase of power consumption of a UEand an increase of interference with, for example, another system due tounnecessary uplink access, it may be prohibited to select, reselect, orcamp on a cell in which a UL CC is not configured.

The following three are disclosed as the method of prohibitingselecting, reselecting, or camping on a cell; (1) using DL/ULlink-information of a cell, (2) using cell barred information, and (3)using a parameter for RACH configuration.

A specific example of the method using the DL/UL link information of acell is disclosed. In a case where the DL/UL link information of a cellindicates that there is no UL CC configuration, the selecting,reselecting, or camping on this cell by the UE is prohibited. This maybe pre-determined in, for example, specifications in a static manner.The UE is capable of judging whether or not selecting, reselecting, orcamping on the cell is prohibited from the DL/UL link information of acell.

A specific example of the method using the cell barred information isdisclosed. A parameter indicating the cell barred information may beprovided. CellBarred may be used as the parameter indicating the cellbarred information. As to a cell in which a UL CC is not configured, theinformation indicating being barred, that is, prohibition is set inCellBarred. CellBarred is broadcast to UEs being served by a cell assystem information. CellBarred may be included in the SIB1 to bebroadcast. In a case where the received CellBarred is the informationindicating being barred, selecting, reselecting, or camping on this cellby the UE is prohibited. This allows the UE to judge whether or notselecting, reselecting, or camping on this cell is prohibited from theparameter indicating the cell barred information.

This method is in accordance with the conventional method regardingCellBarred, and thus, it is not required to separately predetermine theabove in specifications or the like in a static manner. Further, thismethod is in accordance with the conventional method regardingCellBarred, which is applicable also to a case in which a Release 8 or9-compliant UE cannot obtain the information newly provided in thepresent embodiment, such as the DL/UL link information of a cell.

A specific example of the method using the parameter for RACHconfiguration is disclosed. As to a cell in which a UL CC is notconfigured, a value of the parameter for RACH configuration in thesystem information of the DL CC is not set, or the parameter is notmapped on the system information. The cell broadcasts the systeminformation to UEs being served thereby. In a case where the receivedsystem information includes no value of the parameter for RACHconfiguration, or the received system information includes no parameterfor RACH configuration, selecting, reselecting, or camping on that cellby the UE is prohibited. This may be predetermined in, for example,specifications in a static manner. Accordingly, the UE is capable ofjudging whether or not selecting, reselecting, or camping on the cell isprohibited from the parameter for RACH configuration of the cell.

The parameter for RACH configuration may be, for example, “PRACH-Config”indicating the preamble sequence information of the RACH or“RACH-ConfigCommon” being the information required for random access.

FIG. 20 is a flowchart showing a procedure by an eNB regarding theprocess of setting the system information (SI) of a cell in a case wherethe DL/UL link information of the cell is used. FIG. 21 is a flowchartshowing a procedure by a UE regarding the process of prohibiting a UEfrom selecting, reselecting, or camping on a cell in which a UL CC isnot configured in a case where the DL/UL link information of the cell isused. In the present embodiment, the parameter “ULCCconfig” indicatingthe presence or absence of the UL CC configuration is used as the DL/ULlink information of a cell. The flowchart shown in FIG. 21 is similar tothe flowchart of FIG. 12 described above, and the same steps are denotedby the same reference symbols and the common description is not givenhere.

An eNB sets the system information (SI) based on the UL CC configurationof a cell. Specifically, first, in Step ST2001 of FIG. 20, the eNBjudges whether or not a UL CC is configured in a cell, that is, whetheror not a UL CC configuration is provided in the cell. The eNB moves toStep ST2003 in a case of judging that the UL CC configuration isprovided, or moves to Step ST2002 in a case of judging that the UL CCconfiguration is not provided.

In Step ST2002, the eNB sets “0” indicating that the UL CC configurationis not provided in the parameter “ULCCconfig” and moves to Step ST2004.

In Step ST2003, the eNB sets “1” indicating that the UL CC configurationis provided in the parameter “ULCCconfig” and moves to Step ST2004.

In Step ST2004, the eNB causes the MIB of the cell to include“ULCCconfig” being the DL/UL link information of the cell and moves toStep ST2005.

In Step ST2005, the eNB maps the MIB to the PBCH of the DL CC andbroadcasts the MIB to UEs being served thereby. The MIB includes“ULCCconfig” being the DL/UL link information of the cell. The eNB endsthe entire procedure after ending the process of Step ST2005.

In Step ST1204 of FIG. 21, the UE that has selected the cell receivesthe PBCH of the cell and receives the MIB. After that, the UE moves toStep ST2006.

In Step ST2006, the UE judges whether or not a UL CC is configured inthe cell, that is, whether or not a UL CC configuration is provided inthe cell from “ULCCconfig” included in the MIB received in Step ST1204.In a case where “ULCCconfig” is “1”, the UE judges that the UL CCconfiguration is provided and moves to Step ST1205. In a case where“ULCCconfig” is “0”, the UE judges that the UL CC configuration is notprovided. In a case of judging that the UL CC configuration is notprovided, the UE cannot select this cell because it is prohibited fromselecting, reselecting, or camping on a cell in which a UL CC is notconfigured. Accordingly, the UE removes this cell from candidate cells,and returns to Step ST1201 again to perform cell search.

This enables to prohibit, in a case where a cell that is configured byonly a resource for DL without a resource for UL to be associated withthe resource for DL is provided, the UE from selecting, reselecting, orcamping on the cell. Accordingly, an increase of power consumption of aUE and an increase of interference with, for example, another system dueto unnecessary uplink access can be suppressed.

The DL/UL link information of a cell is included in the MIB to bebroadcast, whereby the UE is capable of judging the presence or absenceof the UL CC configuration at an early stage in cell selection orreselection. This enables to reduce a delay time in the process untilthe cell selection or reselection.

FIG. 22 is a flowchart showing a procedure by an eNB regarding theprocess of setting the system information (SI) of the cell in a casewhere cell barred information is used. FIG. 23 is a flowchart showing aprocedure by a UE regarding the process of prohibiting a UE fromselecting, reselecting, or camping on a cell in which a UL CC is notconfigured in a case where the cell barred information is used. Theflowchart shown in FIG. 23 is similar to the flowchart of FIG. 12described above described above, and the same steps are denoted by thesame reference symbols and the common description is not given here.

The eNB sets the system information (SI) based on the UL CCconfiguration of a cell. Specifically, first, in Step ST2101 of FIG. 22,the eNB judges whether or not a UL CC is configured in a cell, that is,whether or not a UL CC configuration is provided in the cell. The eNBmoves to Step ST2103 in a case of judging that the UL CC configurationis provided, or moves to Step ST2102 in a case of judging that the UL CCconfiguration is not provided.

In Step ST2102, the eNB sets “barred” indicating being barred, that is,prohibition in Cellbarred and moves to Step ST2104.

In Step ST2103, the eNB sets “notbarred” indicating not being barred,that is, no prohibition in Cellbarred and moves to Step ST2104.

In Step ST2104, the eNB causes the SIB1 of the cell to includeCellbarred and moves to Step ST2105.

In Step ST2105, the eNB maps the SIB1 to the PDSCH of the DL CC andbroadcasts the SIB1 to UEs being served by the cell. The SIB1 includesCellbarred. The eNB ends the entire procedure after ending the processof Step ST2105.

In Step ST1205 of FIG. 23, the UE that has selected the cell receivesthe DL-SCH to be mapped to the PDSCH of this cell and receives the SIB1. After that, the UE moves to Step ST2106.

In Step ST2106, the UE judges whether or not the cell is barred fromCellbarred included in the SIB1 received in Step ST1205. In a case whereCellbarred is “notbarred”, the UE judges that the cell is not barred andmoves to Step ST1206. In a case where Cellbarred is “barred”, the UEjudges that the cell is barred. In this case, the UE is prohibited fromselecting, reselecting, or camping on the barred cell. Accordingly, theUE cannot select this cell, and thus removes this cell from candidatecells and returns to Step ST1201 again to perform cell search.

As described above, a value indicating barring is set in CellBarred of acell in which a UL CC is not configured, and is broadcast to UEs beingserved by a cell. This enables the UE that has received the broadcastinformation to select, reselect, or camp on this cell, and an increaseof power consumption of a UE and an increase of interference with, forexample, another system due to unnecessary uplink access can besuppressed.

This method is in accordance with the conventional CellBarred method,and thus, there is no need to separately predetermine specifications orthe like in a static manner. This method is applicable also to a case inwhich a Release 8 or 9-compliant UE cannot obtain the information newlyprovided in the present embodiment, such as the DL/UL link informationof a cell.

As described above, in a case where the UE is prohibited from selecting,reselecting, or camping on a cell in which a UL CC is not configured,such a problem arises that the UE that needs only downlink communicationcannot select, reselect, or camp on this cell though it can performcommunication using this cell.

In order to solve this problem, uplink access is prohibited in a cell inwhich a UL CC is not configured and selecting, reselecting, or campingon this cell is not prohibited.

The following four are disclosed as the method of prohibiting uplinkaccess to the cell; (1) using the DL/UL link information of a cell, (2)using the information for stochastically prohibiting access, (3) usingthe information indicating whether or not to prohibit access, and (4)using a parameter for RACH configuration.

A specific example of the method of (1) using the DL/UL link informationof a cell is disclosed. In a case where it is indicated that the UL CCconfiguration is not provided by the DL/UL link information of a cell,the UE is prohibited from accessing this cell or does not access thiscell. This may be predetermined in, for example, specifications in astatic manner. The UE is capable of judging whether or not it isprohibited from accessing this cell or does not access this cell fromthe DL/UL link information of a cell.

A specific example of the method of (2) using the information forstochastically prohibiting access is disclosed. A parameter indicatingthe information for stochastically prohibiting access may be provided.Access class barring (ACB) may be used as the parameter indicating theinformation for stochastically prohibiting access. The access classincluding all UEs that have performed camping on may be provided, and anACB factor (ac-BarringFactor) for determining the barring probability ofthe access class, that is, the prohibition probability thereof may beset to “0” such that access is disabled. In a case where the ACB factoris “0”, access is always barred, that is, prohibited. The cell notifiesUEs being served thereby of the ACB factor. In a case where the ACBfactor of the access class is “0”, the UE is prohibited from accessingthis cell or does not access this cell. The UE is capable of judgingwhether or not the UE is prohibited from accessing this cell or does notaccess this cell from the ACB factor of the access class.

This method is in accordance with the conventional ACB method, and thus,there is no need to separately predetermine specifications or the likein a static manner. In addition, this method is in accordance with theconventional ACB method, and thus is applicable also to a case in whicha Release 8 or 9-compliant UE cannot obtain the information newlyprovided in the present embodiment, such as the DL/UL link information.

A specific example of the method of (3) using the information indicatingwhether or not to prohibit access is disclosed. A parameter indicatingthe information indicating whether or not to prohibit access may beprovided. The parameter indicating the information indicating whether ornot to prohibit access is, for example, “Ac-barringForNoUL”. Values ofthe parameter indicating the information indicating whether or not toprohibit access are two values “1” and “0”. It is indicated that accessis prohibited in the case where the parameter “Ac-barringForNoUL” is“1”, and that access is not prohibited in the case where the parameter“Ac-barringForNoUL” is “0”. As a result, a cell can explicitly notifyUEs being served thereby of whether or not access is prohibited. The UEis capable of judging whether or not the UE is prohibited from accessingthe cell or does not access the cell from the information indicatingwhether or not to prohibit access.

A specific example of the method of (4) using a parameter for RACHconfiguration is disclosed. As to the cell in which a UL CC is notconfigured, a value of the parameter for RACH configuration in thesystem information of the DL CC is not set, or the parameter is notmapped on the system information. The cell broadcasts the systeminformation to UEs being served thereby. In a case where the receivedsystem information does not include the value of the parameter for RACHconfiguration or does not include the parameter for RACH configuration,the UE is prohibited from accessing the cell or does not access thecell. This may be predetermined in, for example, specifications in astatic manner. The UE is capable of judging whether or not it isprohibited from accessing this cell or does not access this cell fromthe DL/UL link information of a cell. The parameter for RACHconfiguration may be, for example, “PRACH-Config” indicating thepreamble sequence information of the RACH, or “RACH-ConfigCommon” beingthe information required for random access.

FIG. 24 is a flowchart showing a procedure by an eNB regarding theprocess of setting the system information (SI) of a cell in a case whereuplink access is prohibited using the DL/UL link information. FIG. 25 isa flowchart showing a procedure by a UE regarding the process ofprohibiting a UE from performing uplink access in a cell, in which a ULCC is not configured, using DL/UL link information of the cell. In thepresent embodiment, the parameter “ULCCconfig” indicating the presenceor absence of the UL CC configuration is used as the DL/UL linkinformation of a cell. The flowchart shown in FIG. 25 is similar to theflowchart of FIG. 12 described above, and the same steps are denoted bythe same reference symbols and the common description is not given here.

The eNB sets the system information (SI) based on the UL CCconfiguration of a cell. Specifically, first, in Step ST2201 of FIG. 24,the eNB judges whether or not a UL CC is configured in a cell, that is,whether or not the UL CC configuration is provided in the cell. The eNBmoves to Step ST2203 in a case of judging that the UL CC configurationis provided, or moves to Step ST2202 in a case of judging that the UL CCconfiguration is not provided.

In Step ST2202, the eNB sets “0” indicating that the UL CC configurationis not provided in the parameter “ULCCconfig”, and moves to Step ST2204.

In Step ST2203, the eNB sets “1” indicating that the UL CC configurationis provided in the parameter “ULCCconfig”, and moves to Step ST2204.

In Step ST2204, the eNB causes the SIB1 of the cell to include“ULCCconfig” being the DL/UL link information of a cell and moves toStep ST2205.

In Step ST2205, the eNB maps the SIB1 to the PDSCH of the DL CC andbroadcasts the SIB 1 to UEs being served by the cell. The SIB 1 includes“ULCCconfig”. The eNB ends the entire procedure after ending the processof Step ST2205.

In Step ST1205 of FIG. 25, the UE that has selected the cell receivesthe SIB1 of the cell. After that, the UE moves to Step ST2206.

In Step ST2206, the UE judges whether or not a UL CC is configured inthe cell, that is, whether or not the UL CC configuration is provided inthe cell from “ULCCconfig” included in the SIB1 received in Step ST1205.In a case where “ULCCconfig” is “1”, the UE judges that the UL CCconfiguration is provided and moves to Step ST1206. In a case where“ULCCconfig” is “0”, the UE judges that the UL CC configuration is notprovided and moves to Step ST2207.

In Step ST2207, the UE performs setting to prohibit uplink access andmoves to Step ST2208.

In Step ST2208, the UE judges whether or not the TAC of the SIB1 isidentical to the TAC of the UE. In a case of judging that the TAC of theSIB1 is identical to the TAC of the UE in Step ST2208, the UE does notneed uplink access and thus enters an idle state operation. In a casewhere the UE judges that the TAC of the SIB1 is not identical to the TACof the UE, that is, judges that the TAC of the SIB 1 is different fromthe TAC of the UE in Step ST2208, the TAU is required. However, uplinkaccess is prohibited in Step ST2207, and thus, the UE is not allowed toinitiate the TAU process. Accordingly, the UE cannot select, reselect,or camp on the cell and removes the cell from candidate cells, andreturns to Step ST1201 again to perform the cell search process.

The UE that has moved to the idle state operation in Step ST2208 isprohibited from uplink access in Step ST2207, and thus is capable ofonly downlink communication. The UE that needs uplink communication mayreturn to Step ST1201 again to perform the cell search process at apoint in time when uplink access is required. Alternatively, the UE mayjudge whether or not the own UE needs uplink access in the judgmentprocess of Step ST2208 and may return to Step ST1201 again to performthe cell search process if uplink access is required. In a case whereuplink access is not required, the UE may enter the idle stateoperation.

This enables to prohibit uplink access of a UE in a case where a cell,which is configured by only a resource for DL without a resource for ULto be associated with the resource for DL, is configured. Accordingly,an increase of power consumption of a UE and an increase of interferencewith, for example, another system due to unnecessary uplink access canbe suppressed. In addition, the UE is not prohibited from selecting,reselecting, or camping on a cell in which a UL CC is not configured,whereby the UE that needs only downlink communication is capable ofselecting, reselecting, or camping on this cell. Therefore, the UE canperform downlink communication.

FIG. 26 is a flowchart showing a procedure by an eNB regarding theprocess of setting the system information (SI) of a cell in a case wherethe information for stochastically prohibiting access is used. FIG. 27is a flowchart showing a procedure by a UE regarding the process ofprohibiting a UE from performing uplink access in a cell in which a ULCC is not configured in a case where the information for stochasticallyprohibiting access is used. The flowchart shown in FIG. 27 is similar tothe flowchart of FIG. 12 described above, and the same steps are denotedby the same reference symbols and the common description is not givenhere.

The eNB sets the system information (SI) based on the UL CCconfiguration of a cell. Specifically, in Step ST2301 of FIG. 26, theeNB judges whether or not a UL CC is configured in the cell, that is,whether or not the UL CC configuration is provided in the cell. The eNBmoves to Step ST2303 in a case of judging that the UL CC configurationis provided or moves to Step ST2302 in a case of judging that the UL CCconfiguration is not provided.

In Step ST2302, the eNB sets “0” in an ACB factor (ac-BarringFactor) andmoves to Step ST2304.

In Step ST2303, the eNB sets a value (in this case, “x”) derived basedon the congested situation of a cell in the ACB factor(ac-BarringFactor) and moves to Step ST2304.

In Step ST2304, the eNB causes the SIB2 of the cell to include the ACBfactor (ac-BarringFactor) and moves to Step ST2305.

In Step ST2305, the eNB maps the SIB2 to the PDSCH of the DL CC andbroadcasts the SIB2 to UEs being served by the cell. The SIB2 includesthe ACB factor (ac-BarringFactor). The eNB ends the entire procedureafter ending the process of Step ST2305.

In Step ST2306 or Step ST2307 of FIG. 27, the UE that has selected thecell receives the SIB2 of the cell. The UE that has received the SIB2 inStep ST2306 does not need uplink access, and then performs an idle stateoperation. The UE that has received the SIB2 of the cell in Step ST2307moves to Step ST2308.

The UE that has received the SIB2 in Step ST2307 requires uplink accessfor initiating the TAU process and, in Step ST2308, judges whether ornot “0” is set in the ACB factor (ac-BarringFactor) included in theSIB2. In a case of judging that “0” is not set in the ACB factor(ac-BarringFactor), the UE performs uplink access through the ACBprocess in the conventional LTE.

Specifically, the UE judges whether or not it is allowed tostochastically perform uplink access in accordance with the value of theACB factor (ac-BarringFactor), and performs uplink access for the TAUprocess if it is allowed, or stands by for a predetermined period andperforms the ACB process again if it is not allowed. In a case ofjudging that “0” is set in the ACB factor (ac-BarringFactor) in StepST2308, the UE judges that uplink access is prohibited and removes thiscell from candidate cells. Then, the UE returns to Step ST1201 again toperform the cell search process.

Through the above, similar effects to those of the case described in theexample shown in FIG. 24 and FIG. 25 can be achieved. In addition, theexample disclosed in FIG. 27 is in accordance with the conventional ACBmethod, and thus does not need to be separately predetermined in, forexample, specifications in a static manner. Further, this example is inaccordance with the conventional ACB method, and thus is applicable alsoto a case where a Release 8 or 9-compliant UE cannot obtain theinformation newly provided in the present embodiment, such as the DL/ULlink information of a cell.

In this case, if a UE that needs two-way communication service selectsor reselects a cell in which a UL CC is not configured, the UE camps onthis cell though it is not allowed uplink access. This causes a problemthat demands for two-way communication service cannot be satisfied.

In order to solve this problem, therefore, in a case where theabove-mentioned DL/UL link information of a cell, the information forstochastically prohibiting access, the information indicating whether ornot to prohibit access, or the parameter for RACH configurationindicates that uplink access to the cell is prohibited, a UE that needstwo-way communication service may avoid selecting, reselecting, orcamping on this cell. Particularly in a case where the DL/UL linkinformation of a cell or the parameter for RACH configuration is used,it is clear that a UL CC is not configured in that cell, which issuitable for solving the above-mentioned problem.

According to the method disclosed in the present embodiment as describedabove, an eNB and a UE communicate with each other using thenon-associated cell being the cell that includes a resource for DL butdoes not include a resource for UL. This eliminates the need to alwaysreserve a resource for UL in the same frequency band as that of aresource for DL in a communication system. This enables to allocate aresource for UL that becomes unnecessary to another cell, anotheroperator, another system, or the like. Therefore, it is possible toimprove the use efficiency of frequency resources.

The present embodiment discloses a method of allowing a CA-compliant UEthat needs uplink access to perform two-way communication using a cellin which a UL CC is not configured. As this method, it suffices thatthis cell is used as a cell for CA (serving cell) in the presentembodiment. On that occasion, CA may be performed to include at leastone serving cell in which a UL CC is configured. Uplink access is madeusing the serving cell in which a UL CC is configured. The serving cellin which a UL CC is configured may serve as PCell. The UE may transmitthe uplink control information regarding a serving cell in which a UL CCis not configured, for example, the CQI for downlink data and theAck/Nack for downlink data, with the use of the serving cell in which aUL CC is configured.

This allows a UE having the capability of supporting CA to performtwo-way communication with the use of a cell in which a UL CC is notconfigured.

It suffices that in this case, a cell in which a UL CC is not configuredis prohibited from serving as PCell and that the use thereof is limitedto SCell. Although the cell for which the UE performs RRC connectionserves as PCell, in a cell in which a UL CC is not configured, the UEcannot perform uplink access for RRC connection. Therefore, if the cellin which a UL CC is not configured is prohibited from serving as PCell,the UE allows a cell in which a UL CC is configured to serve as PCelland is allowed CA. In addition, it is possible to prevent a UE fromunnecessarily performing the RRC connection process in a cell in which aUL CC is not configured.

FIG. 28 is a diagram for describing cells for use in CA in the firstembodiment of the present invention. A cell1 is configured by a DL CC1and a UL CC1. The carrier frequency of the UL CC1 to be associated withthe DL CC1 is shown in the DL/UL link (link) information of the cell. Acell2 is configured by only a DL CC2, where a UL CC is not configured.Therefore, it is indicated that a UL CC is not configured as the DL/ULlink information of a cell. The cell1 corresponds to an associated cell,the DL CC1 corresponds to another resource for downlink, and the UL CC1corresponds to a resource for uplink. The cell2 corresponds to anon-associated cell, and the DL CC2 corresponds to a resource fordownlink.

FIG. 29 is a diagram showing an example of a sequence of CA in a casewhere a cell in which a UL CC is not configured is used. In Step ST2501,the UE that has camped on the cell1 notifies the cell1 of an RRCconnection request. The UL CC1 is configured in the cell1, where uplinkaccess is allowed. Accordingly, in Step ST2502, the cell1 notifies theUE of an RRC connection setup message.

In Step ST2503, the UE that has received the RRC connection setupmessage and performed the setup process for RRC connection notifies thecell1 of an RRC connection setup complete message.

In Step ST2504, the eNB or cell1 determines to perform CA on the cell2for the UE. For example, this is a case where communication service inwhich an amount of downlink data to a UE is larger than an amount ofuplink data occurs, such as download of high capacity data, for example,images.

In Step ST2505, the cell1 notifies the UE of an RRC connectionreconfiguration message for CA. The RRC connection reconfigurationmessage contains the information of the cell2 as a serving cell on whichCA is performed, specifically, the information indicating the addition(Add) of the DL CC2, the system information regarding the cell2, theinformation indicating that a UL CC is not configured, and the like.Through reception of the above-mentioned information, the UE is capableof recognizing that CA is performed on the DL CC2 of the cell2 inaddition to the cell1.

The UE that has received the RRC connection reconfiguration messageprepares for the CA process on the cell1 and cell2 and, in Step ST2506,notifies the cell1 of an RRC connection reconfiguration completemessage.

The cell1 or eNB that has received the RRC connection reconfigurationcomplete message performs CA on the cell2 in addition to the cell1. Thecell1 serves as PCell.

In Step ST2507, downlink communication and uplink communication areperformed between the UE and cell1. In Step ST2508, downlinkcommunication is performed between the UE and cell2.

The downlink communication and uplink communication of Step ST2507 areperformed using the DL CC1 and the UL CC1. The downlink communication ofStep ST2508 is performed using the DL CC2. In other words, downlinkcommunication is performed using the cell1 and the cell2, and uplinkcommunication is performed using the cell1. The UE transmits the uplinkcontrol information for downlink data of the cell2, for example, the CQIfor downlink data, Ack/Nack for downlink data, and the like, with theuse of the cell1 in which a UL CC is configured.

According to the CA method disclosed in the present embodiment asdescribed above, asymmetrical CA is allowed without reserving a resourcefor UL in the same frequency band as that of a resource for DL in acommunication system.

Therefore, a resource for UL that becomes unnecessary can be allocatedto another cell, another operator, another system, or the like, whichenables to improve the use efficiency of frequency resources.

As described above, the UE synchronizes the cells by the PCIs in cellsearch, and detects (specifies) the PCIs of the synchronized cells. ThePCI allocated per cell is used when deriving a code for RS of the cell.The code for RS of the cell is derived from the specified PCIs of thesynchronized cells, to thereby detect RS and measure RS received power.The RS is used as a reference signal for received data demodulation by aUE. That is, the RS is used as a phase synchronization signal for phaseadjustment. In this manner, the PCI allocated per cell is required forcommunication with the cell.

The UE does not search and detect a cell serving as SCell in a case ofperforming CA. Therefore, the UE cannot detect (specify) the PCI fromthe synchronization signal (SS) of a cell in cell search, as in theconventional method. For this reason, the UE cannot recognize the PCI ofSCell and detect RS or the like, which disables the measurement of theRS received power and communication with SCell.

The method for solving this problem is disclosed. The eNB or cellnotifies the UE for which CA is performed of the PCI of SCell on whichCA is performed, through dedicated RRC signaling. The RRC connectionreconfiguration message may be used or may be notified together with theinformation of the serving cell on which CA is performed. For example,in Step ST2505 of FIG. 29 described above, the cell1 causes the RRCconnection reconfiguration message notified the UE for CA to contain thePCI of the cell2 as the information of the cell2 being a serving cell onwhich CA is performed. The UE is capable not only of measuring the RSreceived power of the cell2 but also of communicating with the cell2through the reception of the PCI.

This example has described the case in which the PCI is included in theRRC connection reconfiguration message and notified the UE, as theinformation of the serving cell on which CA is performed. Alternatively,the information of the serving cell on which CA is performed may be theinformation regarding the PCI. The information regarding the PCI doesnot need to be the PCI value per se, but may be, for example, thenumbers in a case where the PCI values are numbered. In a case wherethere are, for example, 504 PCIs as described above, PCI values may benumbered 0 to 503 in specifications and those numbers may be notified.This enables to reduce an amount of information required for notifying aUE. A new parameter indicating the information regarding the PCI may beprovided. For example, the parameter is Cellpci. A value of PCI or thenumber indicating the PCI value is set in Cellpci and is notified theUE.

In the case where the PCI of SCell is identical to the PCI of PCell, itmay be omitted to notify the UE of those. For example, in the case wherethe PCI of a predetermined SCell is the same as the PCI of PCell,Cellpci is not contained in the RRC connection reconfiguration messageas the information of the predetermined SCell. It suffices that in acase where the RRC connection reconfiguration message does not containthe parameter, the UE judges that the PCI of SCell in which theparameter is not contained is identical to the PCI of PCell to derivethe RS or the like using the PCI. According to the method disclosedabove, the UE is capable of communicating with the SCell on which CA isperformed.

The operator or eNB may set the PCI of each cell in the same eNB, or thecell may set the PCI of the own cell. This enables to flexibly set thePCI of the cell configured by the same eNB, as a system. For example,different PCIs may be set in the all cells, or different PCIs may be setin only cells in the same carrier frequency. In a case where differentPCIs are set in cells in the same carrier frequency, it is not requiredto limit the setting of the PCI between different carrier frequencies.The cell configured by the same eNB may be divided into predeterminedgroups and different PCIs may be set in the all cells of the group.Conversely, the same PCI may be set in the all cells of the group. Theabove-mentioned PCI setting methods may be appropriately combined.

The PCIs of the cells configured by the same eNB can be flexibly set inthis manner, and thus, a large number of eNBs that constitute a largenumber of cells can be arranged flexibly in an area that needs extremelyhigh-speed and high-capacity communication, such as the city center.This enables to construct a high-speed and high-capacity communicationsystem.

Another method for solving the above-mentioned problem is disclosed. Thesame PCI is set in cells on which CA can be performed in the cellsconfigured by the same eNB. The same PCI is set for the PCIs of thecells in which a part or the whole of the coverages overlap each otherat different carrier frequencies. As a result, the PCI of SCell on whichCA is performed becomes identical to the PCI of PCell. Therefore, it isnot required to notify the UE of the PCI of SCell, and it is notrequired to notify the UE of the PCI of SCell on which CA is performedthrough RRC signaling. This enables to reduce a signaling amount.

The methods described above are not limited to the first embodiment butare applicable also to a second embodiment to a fifth embodimentdescribed below, which may be appropriately used in combination.Besides, the methods described above are applicable to CA with the useof a conventional cell configuration.

Second Embodiment

The present embodiment discloses the method of associating the DL CC andUL CC in different frequency bands with each other for solving theproblem described in the first embodiment.

TR 36.815 V9.1.0 (hereinafter, referred to as “Non-Patent Document 10”(Chapter 5.1.3)) by 3GPP describes that the DL CC and UL CC in differentfrequency bands are associated with each other but does not disclose adetailed method how to associate those with each other.

Further, R2-102260 (hereinafter, referred to as “Non-Patent Document11”) by 3GPP describes that a parameter “ul-CarrierFreq” of the SIB2 isused in a case where the UL CC is located in a frequency band differentfrom that of the DL CC.

However, according to Non-Patent Document 8, the frequency band ofuplink that is paired with the frequency band of downlink ispredetermined in FDD, as described above. Therefore, association isperformed in the predetermined frequency bands to be paired with eachother in the conventional DL/UL link using the parameter“ul-CarrierFreq” of the SIB2. Specifically, the cell causes the SIB1 toinclude the frequency band information (freqncyBandIndicator) indicatingthe number of a pair of frequency band of downlink and the frequencyband of uplink to be paired therewith and broadcasts the SIB1 to UEsbeing served thereby. Due to this frequency band information, the DL CCand UL CC configured in a cell are located in the predeterminedfrequency bands to be paired with each other.

Therefore, the DL CC and UL CC in different frequency bands cannot beassociated with each other in the above-mentioned methods.

Therefore, in the present embodiment, in order to associate the DL CCand UL CC in different frequency bands with each other, a cell in whicha resource for UL to be associated with a resource for DL is configuredin a frequency band different from that of the resource for DL, and thecell is configured to broadcast the resource information for UL (uplink)to UEs being served thereby.

FIG. 30 is a diagram showing a cell in which a UL CC to be associatedwith a DL CC is configured in a different frequency band. In the cellshown in FIG. 30, a UL CC1 in a frequency band (band A) different from acorresponding predetermined frequency band (denoted by band B as indownlink) of uplink is associated with a DL CC2 in a frequency band(band B) of downlink. The resource information for UL to be associatedwith a resource for DL is shown in the DL/UL link information of a cell.The cell shown in FIG. 30 is equivalent to an asymmetrical cell.

The following five are disclosed as specific examples of the resourceinformation for UL to be broadcast by a cell to UEs being servedthereby; (1) frequency band in which a UL CC is located, (2) carrierfrequency of a UL CC, (3) bandwidth of a UL CC, (4) raster frequency ina frequency band in which a UL CC is located, and (5) lower cut-offfrequency of a frequency band in which a UL CC is located. Possiblevalues thereof are determined in specifications and numbered in advance,which may be used as the numbers thereof.

In order to configure a UL CC to be associated with a DL CC in adifferent frequency band, the cell broadcasts, to UEs being servedthereby, not only the frequency band information in which a DL CC islocated but also the frequency band information in which a UL CC islocated. This allows the UE to specify the carrier frequency of the ULCC. In addition, the cell may broadcast the frequency band informationin which a UL CC is located to UEs being served thereby such that the UEjudges whether or not to select, reselect, or camp on the cell inaccordance with the capability thereof.

The frequency band information in which a DL CC is located may beincluded in the conventional frequency band information(freqncyBandIndicator), and a new parameter indicating the frequencyband information in which a UL CC is located may be provided. Thisenables to reduce the number of parameters. The frequency bandinformation in which a UL CC is located may be included in the SIB1 tobe broadcast. As a result, the UE can obtain the frequency bandinformation in which a DL CC is located and the frequency bandinformation in which a UL CC is located from the same SIB, so that theprocess can be simplified and power consumption can be reduced.

The cell broadcasts the carrier frequency of a UL CC to be paired with aDL CC to UEs being served thereby, whereby the UE can specify thecarrier frequency of the UL CC.

The cell broadcasts the bandwidth of the UL CC to be paired with the DLCC to UEs being served thereby, which allows the UE to specify thebandwidth of the UL CC.

The raster frequency being a possible value of a carrier frequency isdetermined per system. For example, in a case where a frequency bandallocated to another system is used, the raster frequency of thefrequency band may differ from the raster frequency in the LTE-A.Therefore, it suffices that a cell broadcasts a raster frequency in afrequency band in which a UL CC is located to UEs being served thereby.

The cell may broadcast the lower cut-off frequency of the frequency bandin which a UL CC is located to UEs being served thereby. With the use ofthe above-mentioned information, the UE is capable of specifying thecarrier frequency of the UL CC.

In the LTE, the UE derives the carrier frequency of a DL CC and thecarrier frequency of a UL CC using a predetermined calculation equation(see Non-Patent Document 8). This method may be applied. The cellnotifies the UE of the resource information for DL and the resourceinformation for UL. The notification method may be broadcasting ordedicated RRC signaling, which is used depending on a situation. The UEreceives the resource information for DL and the resource informationfor UL and derives the carrier frequency of the DL CC and the carrierfrequency of the UL CC.

The resource information for DL includes the carrier frequency number(N_DL) of the DL CC, the lower cut-off frequency of the frequency band(FB_DL_1) in which a DL CC is located, the lower cut-off frequencynumber of the frequency band (N_DL_1) in which a DL CC is located, andthe raster frequency (Fr_DL).

The resource information for UL includes the carrier frequency number(N_UL), of the above-mentioned UL CC, the lower cut-off frequency of thefrequency band (FB_UL_1) in which a UL CC is located, the lower cut-offfrequency number of the frequency band (N_UL_1) in which a UL CC islocated, and the raster frequency (Fr_UL).

The carrier frequency of the DL CC (F_DL) is derived using Equation (2)below.F_DL=FB_DL_1+Fr_DL×(N_DL−N_DL_1)  (2)

The carrier frequency of the UL CC (F_UL) is derived using Equation (3)below.F_UL=FB_UL_1+Fr_UL×(N_UL−N_UL_1)  (3)

This enables the UE to specify the carrier frequency of the DL CC andthe carrier frequency of the UL CC.

The cell may notify all of the resource information for DL and theresource information for UL. Alternatively, the cell may notify a partof those values and the other part thereof may be predetermined in, forexample, specifications.

The cell may cause the system information to include the resourceinformation for UL. The system information may be the information of theMIB, SIB, or the like, and the cell may broadcast this information toUEs being served thereby. Accordingly, similar effects to those of thefirst embodiment in which the information indicating that a UL CC is notconfigured is broadcast over the MIB or SIB can be achieved. In a casein which the SIB contains the information indicating that a UL CC is notconfigured, this information may be included in the SIB1 or SIB2. Thisenables to achieve similar effects to those of the first embodimentdescribed above.

FIG. 31 is a flowchart showing a procedure by an eNB regarding theprocess of setting the system information (SI) of a cell. FIG. 32 is aflowchart showing a procedure by a UE in a case where a cell in which aDL CC and a UL CC are configured in different frequency bands isselected. The flowchart shown in FIG. 32 is similar to the flowchart ofFIG. 12 described above, and the same steps are denoted by the samereference symbols and the common description is not given here.

An eNB sets the system information (SI) based on the UL CC configurationof the cell. In the flowcharts shown in FIG. 31 and FIG. 32, theresource information for UL to be set includes a frequency band in whicha UL CC is located, a carrier frequency of the UL CC, and a bandwidth ofthe UL CC. The parameter for RACH configuration to be configured in theUL CC for uplink access is set in accordance with the above-mentionedinformation.

In Step ST2701 of FIG. 31, an eNB judges whether or not a UL CC isconfigured in a frequency band different from that of a DL CC in a cell.The eNB moves to Step ST2702 in a case of judging that a UL CC isconfigured in a different frequency band, or moves to Step ST2703 in acase of judging that a UL CC is not configured in a different frequencyband.

In Step ST2702, the eNB sets a frequency band in which the UL CC is setas the frequency band information for UL, enters the frequency band intothe SIB 1, and moves to Step ST2703.

In Step ST2703, the eNB sets the UL CC carrier frequency information ofthe cell, enters the UL CC carrier frequency information into the SIB2,and moves to Step ST2704.

In Step ST2704, the eNB sets the UL CC frequency bandwidth informationof the cell, enters the UL CC frequency bandwidth information into theSIB2, and moves to Step ST2705.

In Step ST2705, the eNB sets the parameter for RACH configuration of thecell, enters the parameter for RACH configuration into the SIB2, andmoves to Step ST2706.

In Step ST2706, the eNB broadcasts the SIB1 to UEs being served by acell. The SIB 1 includes the frequency band information of a UL CC. TheeNB moves to Step ST2708 after ending the process of Step ST2706.

In Step ST2708, the eNB broadcasts the SIB2 to UEs being served by thecell. The SIB2 includes the UL CC carrier frequency information, UL CCfrequency bandwidth information, and parameter for RACH configuration.The eNB ends the entire procedure after ending the process of StepST2708.

In Step ST1205 of FIG. 32, the UE that has selected the cell receivesthe SIB1 of the cell. In Step ST2707, the UE judges whether or not theUE supports the frequency band of a UL CC. Specifically, the UE firstjudges whether or not the SIB1 includes the frequency band informationof a UL CC.

In a case of judging that the SIB1 does not include the frequency bandinformation of a UL CC, the UE judges that the frequency band of a UL CCis the same frequency band as that of the DL CC, judges that the own UEis compatible with the frequency band of the UL CC, and moves to StepST2709.

In a case of judging that the SIB1 includes the frequency bandinformation of a UL CC, the UE recognizes the frequency band in whichthe UL CC of the cell is configured from the frequency band informationof the UL CC, and judges whether or not the own UE supports thisfrequency band. In a case of judging that the own UE supports thisfrequency band, the UE moves to Step ST2709. In a case of judging thatthe own UE does not support this frequency band, the UE judges thatuplink access cannot be made in this cell, and prohibits this cell frombe selected, reselected, or camped on. Then, the UE removes this cellfrom candidate cells and returns to Step ST1201 again to perform cellsearch.

In Step ST2709, the UE receives the SIB2 of the cell and moves to StepST1206. In Step ST1206, the UE judges whether or not the TAC of the SIB1received in Step ST1205 is identical to the TAC of the own UE, tothereby judge whether or not the TAU is required. In a case of judgingthat the TAC of the SIB1 is identical to the TAC of the own UE, the UEjudges that TAU is not required and enters the idle state operation. Ina case of judging that the TAC of the SIB 1 is not identical to the TACof the own UE, the UE judges that TAU is required and moves to StepST2710.

In Step ST2710, the UE derives the configuration of the UL CC of thefrequency band for UL based on the frequency band for the UL CC, the ULCC carrier frequency, and the UL CC frequency bandwidth obtained throughthe reception of the SIB 1 and SIB2 from the cell, and derives the RACHconfiguration in the UL CC based on the obtained parameter for RACHconfiguration. The UE performs uplink access based on this RACHconfiguration and initiates the TAU process. The UE enters the idlestate operation after the TAU process.

Through the above, also in a case where a cell in which a DL CC and a ULCC are configured in different frequency bands and a UE having thecapability of supporting the different frequency bands selects thiscell, uplink access is allowed in the UL CC configured in a frequencyband different from that of the DL CC. That is, the UE is allowedtwo-way communication in a cell in which a DL CC and a UL CC areconfigured in different frequency bands.

In a case where the carrier frequency (F_UL) of a UL CC is derived usingEquation (3) above, it suffices that the eNB sets, in the systeminformation, the carrier frequency number (N_UL) of a UL CC of the cell,the lower cut-off frequency (FB_UL_1) of the frequency band in which aUL CC is located, the lower cut-off frequency number (N_UL_1) of thefrequency band in which a UL CC is located, and that the rasterfrequency (Fr_UL), and the cell is configured to broadcast this systeminformation to UEs being served thereby. The system information may bethe MIB or SIB. For example, the eNB enters FB_UL_1 and Fr_UL into theSIB1, enters N_UL and N_UL_1 into the SIB2, and broadcasts those. Thisenables the UE that has received the system information from the cell toderive the carrier frequency (F_UL) of the UL CC.

For example, in a case of selecting or reselecting a cell in which a ULCC is configured in a frequency band different from that of a DL CC, aUE capable of transmission/reception in the same frequency band, such asa Release 8 or 9-compliant UE is not allowed uplink access. In a casewhere the UE selects or reselects a cell in which a UL CC is configuredin a frequency band different from that of the DL CC in spite of theabove, uplink access may be performed in this cell.

In order to suppress an increase of power consumption of a UE and anincrease of interference with, for example, another system due tounnecessary uplink access, a UE capable of transmission/reception inonly the same frequency band may be prohibited from selecting,reselecting, or camping on a cell in which a UL CC is configured in afrequency band different from that of a DL CC.

The following two are disclosed as the method of prohibiting a UEcapable of transmission/reception in only the same frequency band fromselecting, reselecting, or camping on the cell; (1) using frequency bandinformation in which a UL CC of a cell is located, and (2) using cellbarred information.

A specific example of the method of (1) using frequency band informationin which a UL CC of a cell is located is disclosed. In a case where thefrequency band information in which a UL CC of a cell is located showsthat a UL CC is configured in a frequency band different from that of aDL CC, a UE capable of transmission/reception in only the same frequencyband is prohibited from selecting, reselecting, or camping on that cell.This may be determined in, for example, specifications in a staticmanner. The UE is capable of judging whether or not the cell isprohibited from being selected, reselected, or camped on from thefrequency band information in which a UL CC of a cell is located.

A specific example of the method of (2) using cell barred information isdisclosed. A parameter indicating cell barred information may beprovided. Cellbarred may be used as the parameter indicating cell barredinformation. A cell in which a UL CC is configured in a frequency banddifferent from that of a DL CC sets the information indicating beingbarred in CellBarred. CellBarred is broadcast to UEs being served by thecell as system information. CellBarred may be included in the SIB1 to bebroadcast.

In a case where the received CellBarred is the information indicatingbeing barred, the UE is prohibited from selecting, reselecting, orcamping on that cell. This enables the UE to judge, from a parameterindicating CellBarred of a cell, whether or not the UE is prohibitedfrom selecting, reselecting, or camping on that cell.

The method using the cell barred information is in accordance with theconventional CellBarred method, where it is not required to separatelypredetermine the cell barred information in specifications or the likein a static manner. Further, this method is in accordance with theconventional CellBarred method, and accordingly, is also applicable to acase where a UE capable of transmission/reception in only the samefrequency band, for example, a Release 8 or 9-compliant UE cannot obtainthe information newly provided in the present embodiment, such as thefrequency band information in which a UL CC of a cell is located.

In a case of the method using the above-mentioned cell barredinformation, however, if a UL CC is configured in a frequency banddifferent from that of a DL CC in a cell, a UE capable oftransmission/reception with the use of the DL CC and UL CC located inthe different frequency bands is also barred.

In order to solve this problem, it suffices to set whether or not a cellis barred in accordance with the UE capability. For example, the classof the UE capability of transmission/reception in only the samefrequency band and the class of the UE capability oftransmission/reception in the different frequency bands are provided.Setting is made using a conventional Cellbarred parameter for the classof the UE capability of transmission/reception in only the samefrequency band, whereas a new CellBarred parameter is provided for theclass of the UE capability of transmission/reception in differentfrequency bands.

For example, the CellBarred parameter for the class of the UE capabilityof transmission/reception in different frequency bands is set to“CellBarred-inter”. The cell in which a UL CC is configured in afrequency band different from that of a DL CC sets, to the parameter“CellBarred-inter”, the information indicating whether or not a UEcapable of transmission/reception in different frequency bands isbarred. For example, “barred” is set in the parameter “CellBarred-inter”in a case where a UE capable of transmission/reception in differentfrequency bands is barred, whereas “notbarred” is set in the parameter“CellBarred-inter” in a case where the UE is not barred.

The parameter “CellBarred-inter” is broadcast to UEs being served by acell as the system information. Specifically, the parameter“CellBarred-inter” may be contained in the SIB1 to be broadcast. Thisenables a UE to receive the parameter “CellBarred-inter” in a similarprocedure to that of the conventional CellBarred.

The cell in which a UL CC is configured in a frequency band differentfrom that of a DL CC sets “barred” in the conventional Cellbarredparameter for the class of the UE capability of transmission/receptionin only the same frequency band, and sets the information indicatingthat a UE capable of transmission/reception in different frequency bandis not barred (notbarred) in parameter “CellBarred-inter”. Through theabove-mentioned setting, it is possible to prohibit a UE capable oftransmission/reception in only the same frequency band from selecting,reselecting, or camping on that cell. Besides, a UE capable oftransmission/reception in different frequency bands can select,reselect, or camp on that cell. In this manner, an appropriate processcan be executed in accordance with the UE capability.

FIG. 33 is a flowchart showing a procedure by an eNB regarding theprocess of setting the system information (SI) of a cell in a case wherethe cell barred information is used. FIG. 34 is a flowchart showing aprocedure by a UE regarding the process of prohibiting a UE fromselecting, reselecting, or camping on a cell in which a UL CC isconfigured in a frequency band different from that of a DL CC in a casewhere cell barred information is used. The flowchart shown in FIG. 34 issimilar to the flowchart of FIG. 12 described above, and the same stepsare denoted by the same reference symbols and the common description isnot given here.

The eNB sets the system information (SI) based on the configuration ofthe UL CC of a cell. In the flowcharts shown in FIG. 33 and FIG. 34, asin the flowcharts shown in FIG. 31 and FIG. 32, the resource informationfor UL to be set includes a frequency band in which a UL CC is located,a carrier frequency of a UL CC, and a bandwidth of a UL CC. The eNB setsthe parameter for RACH configuration to be configured in the UL CC foruplink access in accordance with the above-mentioned information.

In Step ST2801 of FIG. 33, the eNB judges whether or not a UL CC isconfigured in a frequency band different from that of a DL CC, that is,in a different frequency band in a cell. The eNB moves to Step ST2802 ina case of judging that a UL CC is configured in a different frequencyband or moves to Step ST2803 in a case of judging that a UL CC is notconfigured in a different frequency band.

In Step ST2802, the eNB sets “barred” indicating being barred in“Cellbarred” and sets “notbarred” indicating not being barred in“Cellbarred-inter”, to thereby move to Step ST2804.

In Step ST2803, the eNB sets “notbarred” indicating not being barred in“Cellbarred” and sets “notbarred” indicating not being barred in“Cellbarred-inter”, to thereby move to Step ST2805.

In Step ST2804, the eNB sets a frequency band in which the UL CC isconfigured as the frequency band information for UL, and enters thefrequency band into the SIB1, to thereby move to Step ST2805.

In Step ST2805, the eNB causes the SIB1 of the cell to include theCellbarred information and Cellbarred-inter information, and moves toStep ST2806.

In Step ST2806, the eNB sets the UL CC carrier frequency information, ULCC frequency bandwidth information, and parameter for RACH configurationof the cell and enters those into the SIB2, to thereby move to StepST2807.

In Step ST2807, the eNB maps the SIB1 to the PDSCH of the DL CC andbroadcasts the SIB1 to UEs being served thereby. The SIB1 includesCellbarred, Cellbarred-inter, and frequency band information for UL. TheeNB moves to Step ST2812 after ending the process of Step ST2807.

In Step ST2812, the eNB broadcasts the SIB2 to UEs being served by acell. The SIB2 includes the UL CC carrier frequency information, UL CCfrequency bandwidth information, and parameter for RACH configuration.The eNB ends the entire procedure after ending the process of StepST2812.

In Step ST1205 of FIG. 34, the UE that has selected a cell in which thesystem information is set as described above receives the DL-SCH to bemapped to the PDSCH of the cell and receives the SIB1.

Next, in Step ST2808, the UE judges whether or not the own UE supports adifferent frequency band, specifically, whether or not uplink access isallowed in a UL CC configured in a frequency band different from that ofa DL CC from the capability of the own UE. The UE judges that itsupports a different frequency band and moves to Step ST2809 in a caseof judging that uplink access is allowed, or judges that the own UE doesnot support a different frequency band and moves to Step ST2810 in acase of judging that uplink access is not allowed.

In Step ST2809, the UE judges whether or not the cell is barred, thatis, whether or not “Cellbarred-inter” is “barred” from Cellbarred-interincluded in the SIB1. In a case of judging that “Cellbarred-inter” is“barred” in Step ST2809, the UE judges that it is prohibited fromselecting, reselecting, or camping on the cell. Then, the UE removesthis cell from candidate cells and returns to Step ST1201 again toperform cell search. In a case of judging that “Cellbarred-inter” is not“barred”, that is, “notbarred” in Step ST2809, the UE judges that is canselect, reselect, or camp on that cell and moves to Step ST2811.

In Step ST2810, the UE judges whether or not the cell is barred, thatis, whether or not “Cellbarred” is “barred” from Cellbarred included inthe SIB1. In a case of judging that “Cellbarred” is “barred” in StepST2810, the UE judges that it is prohibited from selecting, reselecting,or camping on this cell, and removes this cell from candidate cells.Then, the UE returns to Step ST1201 again and performs cell search. In acase of judging that “Cellbarred” is not “barred”, that is, is“notbarred” in Step ST2810, the UE judges that it can select, reselect,or camp on the cell and moves to Step ST2811.

In Step ST2811, the UE receives the SIB2 of the cell and moves to StepST1206. In Step ST1206, the UE judges whether or not the TAC of the SIB1received in Step ST1205 is identical to the TAC of the own UE, tothereby judge whether or not TAU is required. In a case of judging thatthe TAC of the SIB1 is identical to the TAC of the own UE, the UE judgesthat TAU is not required and enters the idle state operation. In a caseof judging that the TAC of the SIB1 is not identical to the TAC of theown UE, the UE judges that TAU is required and moves to Step ST2813.

In Step ST2813, the UE derives the configuration of the UL CC of thefrequency band for UL based on the frequency band for UL CC, UL CCcarrier frequency, and UL CC frequency bandwidth obtained through thereception of the SIB1 and SIB2 from the cell, and derives the RACHconfiguration in the UL CC based on the obtained parameter for RACHconfiguration. Then, the UE performs uplink access based on this RACHconfiguration and initiates the TAU process. After the TAU process, theUE enters the idle state operation.

Through the above, it is possible to set the cell barred information inwhich a UL CC is configured in a frequency band different from that of aDL CC in accordance with the UE capability. With this method, a UEcapable of transmission/reception in only the same frequency band isbarred and a UE capable of transmission/reception in different frequencybands is not barred, which prevents the UE capable oftransmission/reception in only the same frequency band from performingunnecessary uplink access in that cell. Therefore, it is possible toprevent an increase of power consumption of a UE and an increase ofinterference with, for example, another system.

As another example, the class of the UE capability may be provideddepending on the release supported by a UE. The class of the UEcapability compatible with the releases before Release 9 and the classof the UE capability compatible with the releases after Release 10 maybe provided. Setting may be made using the conventional Cellbarredparameter for the class of the UE capability compatible with thereleases before Release 9, and a new CellBarred parameter may beprovided for the class of the UE capability compatible with the releasesafter Release 10. This also enables to achieve similar effects to thoseof the above-mentioned example.

In a case where a UE capable of transmission/reception in only the samefrequency band is prohibited from selecting, reselecting, or camping ona cell in which a UL CC is configured in a frequency band different fromthat of a DL CC, as in the above-mentioned method, such a problem arisesthat the UE cannot select, reselect, or camp on that cell thoughcommunication is allowed with that cell in a case where the UE requiresonly downlink communication.

In order to solve this problem, in a cell in which a UL CC is configuredin a frequency band different from that of a DL CC, a UE capable oftransmission/reception in only the same frequency band is prohibitedfrom uplink access and is prohibited from selecting, reselecting, orcamping on that cell.

The following three are disclosed as the method of prohibiting uplinkaccess to that cell; (1) using the frequency band information in which aUL CC of a cell is located, (2) using the information for stochasticallyprohibiting access, and (3) using the information indicating whether ornot access is prohibited.

A specific example of the method of (1) using the frequency bandinformation in which a UL CC of a cell is located is disclosed. In acase where the frequency band information in which a UL CC of a cell islocated shows that a UL CC is configured in a frequency band differentfrom that of a DL CC, a UE capable of transmission/reception in only thesame frequency band is prohibited from accessing the cell or does notaccess the cell. This may be predetermined in, for example,specifications in a static manner. The UE is capable of judging, fromthe frequency band information in which a UL CC of a cell is located,whether or not the UE is prohibited from accessing that cell or does notaccess that cell.

A specific example of the method of (2) using the information forstochastically prohibiting access is disclosed. A parameter indicatingthe information for stochastically prohibiting access may be provided.Access class barring (ACB) may be used as the parameter indicating theinformation for stochastically barring access. It suffices that theaccess class of the UE capable of transmission/reception in only thesame frequency band is provided and an ACB factor (ac-BarringFactor) fordetermining a barring probability of that access class is set to “0”, tothereby disable access. In a case where the ACB factor is “0”, access isalways barred.

The cell broadcasts the ACB factor to UEs being served thereby. A UEcapable of transmission/reception in only the same frequency band isprohibited from accessing the cell or does not access the cell in a casewhere the ACB factor of the access class of the own UE is “0”. A UEcapable of transmission/reception in only the same frequency band iscapable of judging whether or not it is prohibited from accessing thecell or does not access the cell from the ACB factor of the accessclass.

This method is compatible with the conventional ACB method, which is notrequired to be separately predetermined in, for example, specifications.In addition, this method is compatible with the conventional ACB method,and thus is applicable also to a case in which, for example, a Release 8or 9-compliant UE cannot obtain the information newly provided in thepresent embodiment, such as the DL/UL link information of a cell.

A specific example of the method of (3) using the information indicatingwhether or not access is prohibited is disclosed. A parameter indicatingthe information indicating whether or not access is prohibited may beprovided. The parameter indicating the information indicating whether ornot access is prohibited is, for example, “Ac-barringForIntrafbandUE”.The information indicating whether or not access is prohibited is shownby two values “1” and “0”, where access is prohibited in a case of “l”and access is not prohibited in a case of “0”. Accordingly, a cell canexplicitly notify a UE capable of transmission/reception in only thesame frequency band of whether or not access is prohibited. A UE capableof transmission/reception in only the same frequency band can judgewhether or not it is prohibited from accessing the cell or does notaccess the cell from the information indicating whether or not access isprohibited.

According to the method disclosed in the present embodiment as describedabove, an eNB and a UE communicate with each other using an asymmetricalcell being a cell including a resource for DL and a resource for ULincluded in a frequency band different from that of the resource for DL.This eliminates the need to always reserve a resource for UL in the samefrequency band as that of the resource for DL in a communication system.This enables to allocate a resource for UL that becomes unnecesary toanother cell, another operator, another system, or the like. Therefore,it is possible to improve the use efficiency of frequency resources.

The present embodiment discloses the method of enabling to perform CA ona CA-compliant UE using the cell in which a UL CC is configured in afrequency band different from that of a DL CC. As this method, in thepresent embodiment, it is allowed to configure a UL CC in a frequencyband different from that of a DL CC also in a DL/UL link throughdedicated RRC signaling. This enables DL/UL link via frequency bands fora UE and enables to perform CA on a cell configured in frequency bandsdifferent between the DL CC and UL CC.

As the method for DL/UL link through dedicated RRC signaling, a UE maybe individually notified of the information regarding a UL CC to belinked. As a specific example of the information regarding a UL CC, theinformation described as a specific example of the resource informationfor UL is applicable.

FIG. 35 is a diagram for describing cells for use in CA in the secondembodiment of the present invention. A cell1 is configured by a DL CC1and a UL CC1 in the same frequency band, that is, in a band A. Thecarrier frequency of the UL CC1 to be associated with the DL CC1 isshown in the DL/UL link information of the cell1. A cell2 is configuredby a DL CC2 and a UL CC2 in a frequency band different from that of theDL CC2. The DL CC2 is located in a frequency band B (band B) and the ULCC2 is located in the frequency band A (band A). The resourceinformation for UL such as the frequency band and carrier frequency ofthe UL CC2 to be associated with the DL CC2 is shown in the DL/UL linkinformation of the cell2. The cell2 is equivalent to an asymmetricalcell.

FIG. 36 is a diagram showing an example of a sequence of CA in a casewhere a cell in which a DL CC and a UL CC are configured in differentfrequency bands is used. The sequence shown in FIG. 36 is similar to thesequence of FIG. 29, and the same steps are denoted by the samereference symbols and the common description is not given here.

In the present embodiment, it is determined in Step ST2504 that CA isperformed on the cell2 for a UE, and then, the process of Step ST3001 isperformed. In Step ST3001, the cell1 notifies the UE of an RRCconnection reconfiguration message for CA. The RRC connectionreconfiguration message contains the information of the cell2 being aserving cell on which CA is performed, specifically, the informationindicating the addition of the DL CC2, the system information regardingthe cell2, the information regarding the UL CC (here, UL CC2) to beassociated with the DL CC2, and the resource information of the UL CC2,for example, the frequency band information and the carrier frequencyinformation of the UL CC2.

The UE that has received the RRC connection reconfiguration messageprepares for the CA process on the cell1 and the cell2 and, in StepST3002, notifies the cell1 of an RRC connection reconfiguration completemessage.

The cell1 or eNB that has received the RRC connection reconfigurationcomplete message performs CA on the cell2 in addition to the cell1. Thecell1 serves as PCell.

In Step ST3003, downlink communication and uplink communication areperformed between the UE and the cell1. In Step ST3004, downlinkcommunication and uplink communication are performed between the UE andthe cell2.

The downlink communication and uplink communication of Step ST3003 areperformed using the DL CC1 and UL CC1.

The downlink communication and uplink communication of Step ST3004 areperformed using the DL CC2 and UL CC2. The uplink control informationfor the downlink data of the cell2, for example, the CQI for downlinkdata and Ack/Nack for downlink data may be transmitted by the UE usingthe UL CC1 of the cell1 in a case where there is no uplink data or maybe transmitted by the UE using the UL CC2 of the cell2. Whethertransmission is performed in the PCell or is performed per serving cellmay be predetermined in, for example, specifications.

According to the CA method disclosed in the present embodiment,asymmetrical CA is allowed without reserving a resource for UL in thesame frequency band as that of a resource for DL in a communicationsystem. This enables to allocate needless resource for UL to anothercell, another operator, another system, or the like. Therefore, the useefficiency of frequency resources can be improved.

In a case where a cell in which a UL CC is configured in a frequencyband different from that of a DL CC is used in CA, only the DL CC of thecell may be configured for CA, and the UL CC associated with this DL CCmay not be configured for CA. In this case, by the DL/UL link (UEspecific link) through dedicated RRC signaling, a UE for which CA isperformed may be notified of the information that the DL CC of the cellis a resource for DL for CA, and the information indicating that thereis no configuration of a UL CC to be associated with this DL CC.

This enables to use a UL CC configured by the DL/UL link of this cell asa resource for UL of another UE. Accordingly, it is possible to furtherimprove the use efficiency of frequency resources.

While the CA in which the cell1 serves as PCell has been described withreference to FIG. 36, CA in which the cell2 serves as Pcell is alsoallowed over the method disclosed in the present embodiment.

In this case, similarly in the case where the cell1 serves as PCell, theUE camps on the cell2 in which a UL CC is configured in a frequency banddifferent from that of a DL CC, performs RRC connection with the cell2,and is notified of the information of the cell1 being a serving cell inwhich CA is performed in the RRC connection reconfiguration message fromthe cell2. Specifically, the information of the cell1 that is notifiedfrom the cell2 includes the information indicating the addition of theDL CC1, the system information regarding the cell1, the informationregarding a UL CC (here, UL CC1) to be associated with the DL CC1, theresource information of the UL CC1, for example, the frequency bandinformation and the carrier frequency information of the UL CC1.

Through the above, a cell such as the cell2 in which a DL CC and a UL CCare configured in different frequency bands is caused to serve as PCell.This increases a possibility that a cell having higher communicationquality will be selected in cell selection by a UE. Further, frequencyresources can be used more flexibly.

First Modification of Second Embodiment

In the present modification, the configuration is made such that forallowing more flexible use of frequencies over different frequencybands, at least one cell in which a resource for UL is configured in afrequency band different from that of a resource for DL is located andone or more cells configured by the resource for UL and another resourcefor DL different from the above-mentioned resource for DL are located.The cell notifies UEs being served thereby of the resource informationfor UL using each resource for DL.

FIG. 37 is a diagram showing the concept of two cells which areconfigured by associating the same UL CC with two DL CCs in differentfrequency bands.

A cell1 is configured by a DL CC1 and a UL CC1 in the same frequencyband, specifically, in a band A. The carrier frequency of the UL CC1 tobe associated with the DL CC1 is shown in the DL/UL link information ofthe cell1. A cell2 is configured by a DL CC2 and a UL CC1 in a frequencyband different from that of the DL CC2. The DL CC2 is located in afrequency band B (band B). The resource information for UL such as thefrequency band and carrier frequency of the UL CC1 to be associated withthe DL CC2 are shown in the DL/UL link information of the cell2. Thecell1 is equivalent to a symmetrical cell, whereas the cell2 isequivalent to an asymmetrical cell.

The resource information and RACH configuration of the UL CC1 shown inthe cell1 and the resource information and RACH configuration of the ULCC1 shown in the cell2 may be identical to each other or different fromeach other. For example, the frequency bandwidth of the UL CC1 may bevaried. Alternatively, the RACH configuration configured in the UL CC1may be varied. It is possible to set an optimum resource for UL per cellby varying the frequency bandwidth and the RACH configuration.

As the method in which a cell broadcasts the resource information for ULusing the resource for DL to UEs being served thereby, the methodsdisclosed in the second embodiment above are applicable, and similareffects to those of the second embodiment can be achieved. Further, in acell in which a resource for DL and a resource for UL are configured inthe same frequency band, the conventional method of notifying afrequency band over the SIB1 or the conventional method of notifying theDL/UL link via SIB2 is applicable. The methods disclosed in the secondembodiment above are applicable as the method of limiting access, CAmethod, and the like.

FIG. 38 is a diagram showing an example of a sequence of CA in a casewhere two cells are configured by associating the same UL CC with two DLCCs in different frequency bands. FIG. 38 shows a case in which a UEcamps on the cell1. The sequence shown in FIG. 38 is similar to thesequence of FIG. 29, and the same steps are denoted by the samereference symbols and the common description is not given here.

As described in Non-Patent Document 1 above, in the currentspecifications, each resource for UL belongs to only one serving cellfor one UE. Therefore, in a case of the configuration as shown in FIG.37, such a problem arises that the UL CC1 cannot take both of the cell1and the cell2 as serving cells in CA. In order to solve this problem, itsuffices that the configuration of the UL CC corresponding to any one ofDL CCs is not provided by a UE specific link.

In the present modification, in Step ST2504 of FIG. 38, the eNB or cell1determines to perform CA on the cell2 for the UE. Here, it suffices thatthe eNB or cell1 makes a decision in consideration of whether or not theUL CC of the cell2 is identical to the UL CC of the cell1. Here, the ULCC of the cell2 is identical to the UL CC of the cell1, and thus the eNBor cell1 determines to perform CA on only the DL CC2 of the cell2.

In Step ST3201, the cell1 notifies the UE of an RRC connectionreconfiguration message for CA. The RRC connection reconfigurationmessage contains the information of the cell2 being a serving cell onwhich CA is performed, specifically, contains the information indicatingthe addition of the DL CC2, the system information regarding the cell2,the information indicating that a UL CC is not configured, and the like.

The UE that has received the RRC connection reconfiguration messageprepares for the CA process on the cell1 and the DL CC2 and, in StepST3202, notifies the cell1 of the RRC connection reconfigurationcomplete message.

The cell1 or eNB that has received the RRC connection reconfigurationcomplete message performs CA on the DL CC2 in addition to the cell1. Thecell1 serves as PCell.

In Step ST3203, downlink communication and uplink communication areperformed between the UE and the cell1. In Step ST3204, downlinkcommunication is performed between the UE and the DL CC2.

The downlink communication and uplink communication of Step ST3203 areperformed using the DL CC1 and the UL CC1. The downlink communication ofStep ST3204 is performed using the DL CC2. That is, downlinkcommunication is performed using the cell1 and the cell2, and uplinkcommunication is performed using the cell1. The UE transmits the uplinkcontrol information for downlink data of the cell2, for example, the CQIfor downlink data, Ack/Nack for downlink data, and the like, using thecell1 in which a UL CC is configured.

The above-mentioned method enables CA also in a case where two cells areconfigured by associating the same UL CC with two DL CCs in thedifferent frequency bands by a DL/UL link of a cell. Accordingly, thefrequency resource can be used more flexibly.

FIG. 39 is a diagram showing another example of the sequence of CA inthe case where two cells are configured by associating the same UL CCwith two DL CCs in different frequency bands. Differently from FIG. 38,FIG. 39 shows the case in which the UE camps on the cell2.

In Step ST3301, the UE that has camped on the cell2 notifies the cell2of an RRC connection request. The cell2 is allowed uplink access becausethe UL CC1 is configured therein.

In Step ST3302, the cell2 notifies the UE of an RRC connection setupmessage. In Step ST3303, the UE that has received the RRC connectionsetup message and performed the setup process for RRC connectionnotifies the cell2 of the RRC connection setup complete message.

In Step ST3304, the eNB or cell2 determines to perform CA on the cell1for the UE. Here, it suffices that the eNB or cell2 makes a decision inconsideration of whether or not the UL CC of the cell1 is identical tothe UL CC of the cell2. In this case, the UL CC of the cell1 isidentical to the UL CC of the cell2, and thus, the eNB or cell2determines to perform CA on only the DL CC1 of the cell1.

In Step ST3305, the cell2 notifies the UE of an RRC connectionreconfiguration message for CA. The RRC connection reconfigurationmessage contains the information of the cell1 being a serving cell onwhich CA is performed, specifically, contains the information indicatingthe addition of the DL CC1, the system information regarding the cell1,the information indicating that a UL CC is not configured, and the like.

The UE that has received the RRC connection reconfiguration messageprepares for the CA process on the cell2 and the DL CC1 and, in StepST3306, notifies the cell2 of an RRC connection reconfiguration completemessage.

The cell2 or eNB that has received the RRC connection reconfigurationcomplete message performs CA on the DL CC1 in addition to the cell2. Thecell2 serves as PCell.

In Step ST3307, downlink communication and uplink communication areperformed between the UE and the cell2. In Step ST3308, downlinkcommunication is performed between the UE and the DL CC1.

The downlink communication and uplink communication of Step ST3307 areperformed using the DL CC2 and the UL CC1.

The downlink communication of Step ST3308 is performed using the DL CC1.The UE transmits the uplink control information for downlink data of thecell1, for example, the CQI for downlink data and Ack/Nack for downlinkdata, and the like, using the cell2 in which a UL CC is configured.

This enables to achieve similar effects to those in the case of thesequence shown in FIG. 38 described above. Besides, the UE can performCA on whichever cell it camps, which increases the possibility that a UEmay select a cell with a link of excellent communication quality.

With the use of the methods disclosed in the first embodiment and thesecond embodiment as described above, in a case where a frequency bandfor downlink and a frequency band for uplink to be paired therewith havebeen configured, it is possible to efficiently use frequency resourcesso as not to cause unused carrier frequency.

The methods disclosed in the first embodiment to the first modificationof the second embodiment may be appropriately combined with each other.This allows flexible use of frequency resources, and thus, useefficiency of frequency resources can be more increased.

Third Embodiment

The present embodiment discloses the configuration of a frequency bandfor allowing more efficient use of frequency resources. In the presentembodiment, a frequency band configured by one or more resources for DLwithout a resource for UL to be associated therewith.

FIG. 40 is a diagram showing the concept of the frequency bandconfigured by one or more resources for DL without a resource for UL tobe associated therewith. The DL CC1 and DL CC2 are configured in thefrequency band for downlink A as resources for DL. The lower cut-offfrequency (F_(DL_low)) of the frequency band for downlink A is FB_DL_1,and the upper limited frequency (F_(DL_high)) thereof is FB_DL_h. Thereis no configuration of a UL CC being a resource for UL to be associatedwith the DL CC1. That is, there is no UL CC configured by the DL/UL linkof the cell of the DL CC1. Similarly, there is no configuration of theUL CC being a resource for UL to be associated with the DL CC2. That is,there is no UL CC configured by the DL/UL link of the cell of the DLCC2.

The frequency band for downlink A is configured by one or more resourcesfor DL without a resource for UL to be associated therewith. In otherwords, one or more resources for DL without a resource for UL areconfigured in the frequency band for downlink A. The one or moreresources for DL are the DL CC1 and DL CC2 in this case. In this manner,the frequency band for downlink A includes resources for DL but does notinclude a resource for UL.

The resources for DL may be contiguous or non-contiguous, or may havedifferent bandwidths. There is no resource for UL, which means that afrequency band for uplink corresponding to a frequency band for downlinkis not required. This enables to configure a frequency band for downlinkin which a frequency band for uplink to be paired therewith is notconfigured.

FIG. 41 is a diagram showing a setting example of a frequency bandconfigured by one or more resources for DL without a resource for UL tobe associated therewith. There is no frequency band for uplink (ULoperating band) as the frequency band (band) A. There exists a frequencyband for downlink (DL operating band), and the lower cut-off frequency(F_(DL_low)) and the upper limited frequency (F_(DL_high)) thereof areset as FB_DL_1 and FB_DL_h, respectively. Only the frequency band fordownlink is set as a frequency band, and a frequency band for uplink isnot set. This is effective in a case where the configuration of afrequency band is predetermined.

Through the above, only a frequency band for downlink is required as anactual frequency resource. This eliminates the need to allocate afrequency band for uplink as an actual frequency resource and reservethe frequency band for uplink, though there is no use of the frequencyband for uplink. Therefore, also in a case where, for example, there isone narrow-band frequency resource, it is possible to configure afrequency band for downlink only. This allows efficient use of frequencyresources in a case where there are discrete and narrow-band frequencyresources.

In a case of the frequency band for downlink disclosed in the presentembodiment, the DL/UL link information of a cell may be reduced in a DLCC configured in that band. In addition, the DL/UL link information ofthe cell is not required to be broadcasted UEs being served by the cell.The frequency band for downlink is shown in the DL CC configured in theband, specifically, is included in the SIB1. In a case where theconfiguration of a frequency band is predetermined in, for example,specifications as shown in FIG. 41, a UE can recognize the configurationin advance.

Therefore, even if not having received the DL/UL link information of acell from that cell, a UE can recognize the configuration of a frequencyband in which that cell is configured, and can recognize that afrequency band for uplink is not configured in that frequency band. Thisenables to recognize that there is no UL CC to be associated with a DLCC of that cell. As a result, the system information of a cell can bereduced, which enables to reduce a signaling amount from a cell to a UE.

Fourth Embodiment

The first embodiment has disclosed the method of providing a cellconfigured by only a resource for DL without a resource for UL to beassociated with the resource for DL. In the present embodiment, a cellconfigured by only a resource for UL without a resource for DL to beassociated with the resource for UL is provided.

FIG. 42 is a diagram showing the concept of a cell configured by only aUL CC without a DL CC to be associated with the UL CC. The cell shown inFIG. 42 is a cell including only a UL CC without a DL CC to beassociated with the UL CC1, which is a cell in which only a resource forUL is reserved. That is, the cell shown in FIG. 42 does not include a DLCC to be associated with a UL CC by the DL/UL link of the cell. With thecell configuration as described above, communication in only uplink canbe performed in that cell, which is effective. The cell shown in FIG. 42is equivalent to a non-associated cell.

In the LTE, the UE cannot perform uplink access in a cell in which a DLCC being a resource for DL is not configured. The UE cannot performcommunication in the cell. In the first place, there is no cell in whicha DL CC is not configured in the LTE.

Therefore, disclosed below is a method in which a UE having thecapability of supporting CA is allowed communication with a cell inwhich a DL CC is not configured. That cell may be used as a cell for CA(serving cell). On that occasion, CA may be performed such that at leastone serving cell in which a DL CC is configured is included. Thedownlink access is allowed with a serving cell in which a DL CC isconfigured, which allows a UE to perform communication.

The eNB may notify the UE of the system information regarding theserving cell including only a UL CC, downlink control information,uplink scheduling information, HARQ for uplink data, and the like, usingthe serving cell in which a DL CC is configured.

This allows an eNB to use a cell in which a DL CC is not configured forthe communication with a UE.

In this case, a cell in which a DL CC is not configured may beprohibited from serving as PCell. This is because a DL CC is requiredfor PCell. A UE does not normally select or reselect a cell in which aDL CC is not configured, and thus, that cell does not serve as PCell.Accordingly, it is not particularly required to explicitly prohibit thatcell from serving as PCell.

FIG. 43 is a diagram for describing cells for use in CA in the fourthembodiment of the present invention. A cell1 is configured by a DL CC1and a UL CC1. The carrier frequency of the UL CC1 to be associated withthe DL CC1 is shown in the DL/UL link information of a cell. A cell2 isconfigured by only a DL CC2 and does not include a UL CC. It is shown asthe DL/UL link information of a cell that a UL CC is not configured. Acell3 is configured by only a UL CC3 and does not include a DL CC.

FIG. 44 is a diagram showing an example of a sequence of CA in a casewhere a cell in which a DL CC is not configured is used. FIG. 44 shows acase in which a UE camps on the cell. The sequence shown in FIG. 44 issimilar to the sequence of FIG. 29, and the same steps are denoted bythe same reference symbols and the common description is not given here.

In the present embodiment, the process of Step ST3801 is performed afterthe UE notifies the cell1 of an RRC connection setup complete message inStep ST2503. In Step ST3801, the eNB or cell1 determines to perform CAon the DL CC2 and the UL CC3 for the UE. The eNB or cell1 associates theDL CC2 and the UL CC3 with each other and sets those.

In Step ST3802, the cell1 notifies the UE of an RRC connectionreconfiguration message for CA. The RRC connection reconfigurationmessage contains the information of the cell2 being a serving cell onwhich CA is performed and the information of the cell3 being a servingcell on which CA is performed. Included as the information of the cell2are, for example, the information indicating the addition of the DL CC2,the system information regarding the cell2, and the informationindicating that the UL CC3 is set as a corresponding UL CC. Included asthe information of the cell3 are, for example, the informationindicating the addition of the UL CC3, the system information regardingthe cell3, and the information indicating that the DL CC2 is set as acorresponding DL CC.

The UE that has received the RRC connection reconfiguration messageprepares for the CA process on the cell1, the DL CC2, and the UL CC3and, in Step ST3803, notifies the cell1 of an RRC connectionreconfiguration complete message.

The cell1 or eNB that has received the RRC connection reconfigurationcomplete message performs CA on the DL CC2 and the UL CC3, in additionto the cell1. The cell1 serves as PCell.

In Step ST3804, downlink communication and uplink communication areperformed between the UE and the cell1. In Step ST3805, downlinkcommunication is performed between the UE and the DL CC2. In StepST3806, uplink communication is performed between the UE and the UL CC3.

The downlink communication and uplink communication of Step ST3804 areperformed using the DL CC1 and the UL CC1. The UE transmits the uplinkcontrol information for downlink data of the DL CC2, for example, theCQI for downlink data, Ack/Nack for downlink data, and the like, usingthe cell1 in which a UL CC is configured, or UL CC3.

The control information for uplink data of the UL CC3, for example, theresource scheduling information and the like are transmitted using theDL CC2 or the DL CC1 of the cell1.

The above-mentioned method enables CA also in a case where a cellincluding only a UL CC without a DL CC to be associated with the UL CC,which has been disclosed in the present embodiment, is configured. Thisallows communication with the UE using that cell. Accordingly, in a casewhere there is space only in the frequency resource for uplink, moreflexible use of frequency resources, such as the use of the presentembodiment, is allowed, which more increases the use efficiency offrequency resources.

Fifth Embodiment

The present embodiment discloses the configuration of a frequency bandfor allowing more efficient use of frequency resources. In the presentembodiment, a frequency band configured by one or more resources for ULwithout a resource for DL to be associated therewith is provided.

FIG. 45 is a diagram showing the concept of a frequency band configuredby one or more resources for UL without a resource for DL to beassociated therewith. The UL CC1 and the UL CC2 are configured in thefrequency band for uplink B as resources for UL. The lower cut-offfrequency (F_(UL_low)) and upper limited frequency (F_(UL_high)) of thefrequency band for uplink B are FB_UL_1 and FB_UL_h, respectively. Thereis no configuration of the DL CC being a resource for DL to beassociated with the UL CC1. Similarly, there is no configuration of theDL CC being a resource for DL to be associated with the UL CC2.

The frequency band for uplink B is configured by one or more resourcesfor UL without a resource for DL to be associated therewith. In otherwords, one or more resources for UL without a resource for DL areconfigured in the frequency band for uplink B. The one or more resourcesfor UL are the UL CC1 and UL CC2 in this case. In this manner, thefrequency band for uplink B includes a resource for UL but does notinclude a resource for DL.

The resources for UL may be contiguous or non-contiguous, or may havedifferent bandwidths. There is no resource for DL, which means that afrequency band for downlink corresponding to a frequency band for uplinkis not required. This enables to configure a frequency band for uplinkin which a frequency band for downlink to be paired therewith is notconfigured.

FIG. 46 is a diagram showing a setting example of a frequency bandconfigured by one or more resources for UL without a resource for DL tobe associated therewith. There exists a frequency band for uplink (ULoperating band) as the frequency band B, and the lower cut-off frequency(F_(UL_low)) and upper limited frequency (F_(UL_high)) thereof are setas FB_UL_1 and FB_UL_h, respectively. There is no frequency band fordownlink (DL operating band). In this manner, only the frequency bandfor uplink is set as a frequency band and a frequency band for downlinkis not set. This is effective in a case where the configuration of thefrequency band is predetermined.

Through the above, only a frequency band for uplink is required as anactual frequency resource. This eliminates the need to allocate afrequency band for downlink as an actual frequency resource and reservethe frequency band for downlink, though there is no use of the frequencyband for downlink. Therefore, also in a case where, for example, thereis one narrow-band frequency resource, it is possible to configure afrequency band for uplink only. This allows efficient use of frequencyresources in a case where there are discrete and narrow-band frequencyresources.

The methods disclosed in the first embodiment to the fifth embodimentmay be appropriately combined with each other. Accordingly, also in acase where there are discrete and narrow-band frequency resources, theuse efficiency of frequency resources can be increased.

The present invention is also applicable to a system (hereinafter,referred to as “downlink communication service system” in some cases)that provides services in which only downlink communication isperformed, such as ETWS, CMAS, and multimedia broadcast multicastservices (MBMS). The downlink communication service system may besupported in a resource for DL in which a corresponding resource for ULis not configured. This allows a UE having the capability correspondingto a downlink communication service system to provide a downlinkcommunication service using the resource for DL.

The frequency band for downlink that is configured by a resource for DLand does not include a resource for UL may be provided for a downlinkcommunication service system. This allows a UE, which supports afrequency band for downlink for a downlink communication service systemand has the capability corresponding to a downlink communication servicesystem, to provide a downlink communication service using the resourcefor DL in the frequency band for downlink. Accordingly, the useefficiency of frequency resources can be improved.

The methods disclosed in the present invention are applicable not onlyto eNBs/NBs, but also to so-called local nodes such as HeNB, HNB, picoeNB (LTE pico cell (EUTRAN pico cell)), pico NB (WCDMA pico cell (UTRANpico cell)), node for hotzone cells, relay node, and remote radio head(RRH). The present invention is also applicable to cases in which acarrier frequency differs and a frequency band differs per, for example,node type. This enables to improve the use efficiency of frequencyresources.

While each embodiment has mainly described the LTE-A system, thecommunication system of the present invention is also applicable toanother communication system.

For example, only a frequency band for downlink is allocated in abroadcast system. The use of the present invention enables to use thefrequency band for a broadcast system for a communication system,whereby the both systems can be used mutually. The present invention maybe applied to so-called white space. This enables to improve the useefficiency of frequency resources. The white space is described inNon-Patent Document 12 below.

Non-Patent Document 12: Radio Policy Division, Ministry of InternalAffairs and Communications, “Efforts to realize the use of white space”,21st Meeting papers of broadcast system Committee, [online] Oct. 29,2010, Information and Communications Technology Sub-Council, Informationand Communications Council, retrieved Dec. 9, 2010 fromhttp://www.soumu.go.jp/main_content/000087579.pdf

While the invention has been shown and described in detail, theforegoing description is in all aspects illustrative and notrestrictive. It is therefore understood that numerous modifications andvariations can be devised without departing from the scope of theinvention.

DESCRIPTION OF REFERENCE SYMBOLS

71 user equipment device (UE), 72 base station device, 72-1 eNB, 72-2Home-eNB, 73 MME/S-GW unit (MME unit), 74 HeNBGW, CC component carrier,DL downlink, UL uplink.

The invention claimed is:
 1. A communication system comprising aterminal device and a base station that performs radio communicationwith the terminal device, wherein the base station configures anon-associated cell and an associated cell, the non-associated cellincludes only a resource for downlink, the resource for downlink beingallocated to downlink communication from the base station to theterminal device, the non-associated cell not including a resource foruplink, the resource for uplink being allocated to uplink communicationfrom the terminal device to the base station, the associated cellincludes another resource for downlink and a resource for uplink, theanother resource for downlink being allocated to downlink communicationfrom the base station to the terminal device, the resource for uplinkbeing allocated to uplink communication from the terminal device to thebase station, the base station does not transmit a link information ofthe non-associated cell to the terminal device, the base stationtransmits a link information of the associated cell to the terminaldevice, the terminal device performs downlink communication using thenon-associated cell and the associated cell, and the terminal deviceperforms uplink communication using the associated cell.
 2. A basestation performing radio communication with a terminal device, whereinthe base station configures a non-associated cell and an associatedcell, the non-associated cell includes only a resource for downlink, theresource for downlink being allocated to downlink communication from thebase station to the terminal device, the non-associated cell notincluding a resource for uplink, the resource for uplink being allocatedto uplink communication from the terminal device to the base station,the associated cell includes another resource for downlink and aresource for uplink, the another resource for downlink being allocatedto downlink communication from the base station to the terminal device,the resource for uplink being allocated to uplink communication from theterminal device to the base station, the base station does not transmita link information of the non-associated cell, the base stationtransmits a link information of the associated cell, the base stationperforms downlink communication using the non-associated cell and theassociated cell, and the base station performs uplink communicationusing the associated cell.
 3. A terminal device performing radiocommunication with a base station configuring a non-associated cell andan associated cell, wherein the non-associated cell includes only aresource for downlink, the resource for downlink being allocated todownlink communication from the base station to the terminal device, thenon-associated cell not including a resource for uplink, the resourcefor uplink being allocated to uplink communication from the terminaldevice to the base station, the associated cell includes anotherresource for downlink and a resource for uplink, the another resourcefor downlink being allocated to downlink communication from the basestation to the terminal device, the resource for uplink being allocatedto uplink communication from the terminal device to the base station,the terminal device does not receive a link information of thenon-associated cell, the terminal device receives a link information ofthe associated cell, the terminal device performs downlink communicationusing the non-associated cell and the associated cell, and the terminaldevice performs uplink communication using the associated cell.